Gautam,
Welcome to the society of the never-satisfied optically obsessed! As Henry pointed out, any excellent 7x bino is going to provide as much detail as your eyes can use, so you aren't going to find significant differences in optical quality among them using resolution targets or dollar bills. If your desire is to see more detail, you need higher power. You will see more detail with a quality 8, 8.5, or 10x. Personally, I'd recommend a good 8 or 8.5x with a field of view of 7 degrees (365 feet at 1000 yards) or more.
If your goal is to acquire a bino that will out-perform your 7x35, the improvement in performance will be primarily a matter of brightness and ergonomics (including how easily you can quickly bring the bino to your eyes, focus on a bird, and acquire a high-quality image). Here, there are huge differences between models, and issues of personal taste are a much bigger factor in the equation. DON'T UNDERESTIMATE the importance of these ergonomic factors for in-practice image quality. If a bino has superb optics, but is hard to focus quickly, or is harder to hold steady, or has to be held in a very particular orientation to your eyes/glasses to get the best image, it will be MUCH inferior to a more ergonomically compatible model when it comes to what you ACTUALLY GET TO SEE (in terms of both quantity of birds acquired, as well as quality of view), especially if you spend alot of time watching birds places where the opportunities for viewing are fleeting, and the birds are at relatively close but varied distances (flying birds, or birds in woods and brush/marsh habitats).
If you have been using your Nikon 7x35 E regularly, and for a long time, your brain has had a lot of opportunity to adjust to their image and to how to hold them. This makes it harder to quickly evaluate the merits of a prospective replacement. I have found that it is very hard to evaluate binoculars in stores or in my home--you have to test them in the field. Look at strongly backlit subjects, look at very finely detailed subjects with big differences in brightness (like pine or cedar trees, or birds moving from sun to shade in these trees), if you wear glasses, test to see how much the view is compromised when a lateral light source shines on the oculars (I always wear a wide-brimmed hat to deal with this), and test to see how quickly you can acquire birds when they are flitting through brush and foliage. Test to see how comfortable the bino is to use while wearing your favorite pair of gloves. Test the focus stiffness in the cold--unfortunately most porros, including the Nikon Superior E (and, I suspect your 7x35E) become very stiff in the cold, but the top-end roof prism models from Nikon, Zeiss, Leica, and Swarovski are nearly to entirely unafffected.
You note some issues with color and brighness. Small differences in color rendition may be very apparent to you, and you will have a bias based on your current bino, but unless they are extreme, I have found that my brain adjusts after a while such that they do not call attention to themselves in use (though I can still detect them if I direct my attention to the issue). I really like the color rendition of Nikon (which is remarkably consistent from model to model and year to year), but I find the Zeiss 7x42 Classic equally wonderful, and the current models from Swarovski, Zeiss, and Leica are close enough to neutral that the small differences among them are of little if no importance to me. As for brightness--there IS something about the new generation of roof prisms from Leica, and especially Zeiss, that seems different in a sometimes bothersome way that I cannot adequately describe and do not really understand. These models are exceptionally bright, which is a good thing most of the time, but under some conditions of lighting they seem to have something wrong with their contrast. It feels to my eyes/brain almost like a fogging, as if bright things have a halo, though I don't see any halos! I don't know why it is, but sometimes the slightly dimmer view of the BN Leicas and Zeiss Classics seems richer (with truer blacks?) and more contrasty than the newer offerings. I've noticed various others on Birdforum make comments about being bothered by the brightness/contrast of these binos from time to time, though like me, they don't seem to have a handle on what it is that is bothering their brain.
As for your overall goal, I can empathize with your frustration. My own binocular quest began after I replaced a $25 porro with a Bushnell 8x42 Banner (a $110 roof)--(wow!) the improvement in optics and ergonomics was amazing! A few years later, I replaced the Bushnells with the Nikon 8x40 Classic Eagle, which were better (optically and ergonomically) by another order of magnitude! The Nikons were so much better (optically and ergonomically), it blew my mind! I couldn't believe that they could be improved upon optically, but I became obsessed with optical quality in binoculars (and in binoculars generally). At the time, no roof models were phase-coated, so having compared them with the Leica and Zeiss models of that time, I was satisfied that the Nikons were as good as binos could get. Then I got a Bausch & Lomb 7x26 Custom compact--(wow!) the improvement in some undefinable aspect of contrast was obvious, and they were surprisingly bright, but I still preferred full-size binos overall. About that same time, phase-correction coating were introduced, I learned that this was the reason my little 7x26 porros were in some ways optically better than my Nikons, and so I got the Zeiss 7x42 BGATP (Classic). Wow! Although they did not have the fantasticly flat field and edge sharpness of the Nikons, the Zeiss were contrasty, sharp, bright, perfect in my hands, and so easy to look through! Really, could a bino be any more perfect???!!! Well, I sure hoped so, because at that point in my obsession, I couldn't wait to experience yet another big leap in viewing pleasure.
And so began the futile effort to find a better bino than the Zeiss 7x42 Classic. I pictured the perfect bino as a full-sized roof, with the ergonomics, contrast, brightness, and wide field of view of the Zeiss, and the flat field, edge sharpness, waterproofing, and internal focusing of the Nikon. It was this quest, in large measure, that turned me into a binocular collector (Actually, I had already been optically obsessed with camera lenses and slide-viewing loupes, so the bino obsession was not unprecedented, but it gained importance as I spent more time birding and less time taking pictures). Having acquired many binos since then, I have learned that the perfect bino does not exist, that there are many good binoculars, that the "personalities" of individual models are remarkably different, that the best binocular models excel in a range of birding environments, but that no one binocular is perfect for all types of birding. Side comment on scopes--I haven't become obsessed with birding scopes. I find that they do not have as many dimensions to their optical and ergonomic "personalities" as do binos, and that in use, their view is more often shaped by seeing conditions than by their optics. So I am content with my Nikon 78mm Fieldscope ED with wide angle 30x eyepiece (I also have, but rarely use, 50x, 75x and 25-75x eyepieces) which I use heavily. I do have a Nikon 60mm Fieldscope (orginal version, non ED) with 24x wide angle eyepiece which I sometimes use when traveling, and my first scope, a tiny Leupold 25x50 waterproof spotter, which I don't use anymore.
Most of the binos in my "collection" are very good to excellent optically, and nearly all my binos are birding binos (rather than military, nautical, astronomical) in full, 2/3, compact, and pocket sizes of recent vintage. I have both roofs and porros. I am strongly biased toward greater depth of field and field of view, so nearly all my binos are 7 or 8x. I love and hate them all--love because they collectively do what they are supposed to, hate because not a one of them is perfect. All have been used extensively, and I used to try to use each and every one from time to time, but these days I keep most of them stored away. Here are the models I keep handy for regular use:
Swarovski 8.5x42 EL (my favorite birding binocular)
Leica 8x42 Ultravid (preferred over my slow-focus EL in brush/woods)
Zeiss 8x32 FL (my favorite all-around bird/butterfly/travel bino)*
Leica 8x32 BA Ultra (my favorite travel bino for birding)
Zeiss 8x20 Victory (my choice for when I'd rather not carry a bino)
Pentax 6.5x21 Papilio (my favorite butterflying bino)
*The Zeiss FL would be my favorite all-around bino if they fit my hands a little better and weren't so sensitive, at least for me, to eye-glasses-ocular lens alignment for getting the best view.
Which bino of my many excellent binos do I feel worst about relegating to the closet? My Zeiss 7x42 Classic--they are still my all time overall favorite bino (best ergonomics, easiest view), and are unmatched for warblers in the woods and seeing sparrows flitting through shady shrubbery, but I guess the Leica 8x42 Ultravids work well enough in those particular situations that, at least for the time being, they have displaced the Zeiss. Which binos do I most often carry to go birding? The Swarovskis. Which, after the Zeiss Classics, do I most prefer for its handling properties? The Swarovkis. Which bino in my list, to my eyes, provides the most beautiful view of a bird? The Swarovskis.
Which of my binos has the best quality image? The Nikon 8x32 Superior E. These days, there are many binocular models with awesomely good optics, but I don't see how anyone (Dennis?) can dispute the solid optical performance with regard to resolution/sharpness, contrast, color rendition, edge of field quality, relative freedom from distortion, relative freedom from chromatic abberation, and brightness, of the Nikon 8x32 and 10x42 Superior E binoculars. They are also a very solidly constructed. How I miss the days when you could buy the 8x32 Superior E for $420--I recommended them to a lot of people, regardless of how little or how much money they had to spend. Then Nikon raised the price to $600, which made it harder to convince anyone other than true optics fanatics to go for the Superior E (It was hard to convince someone planning to spend $250-350 to spend $600, and at the time, most top roofs could be found for $750-$900, so it became harder to convince folks with more money not to get a roof). Now that top roofs cost $1000-$1600, the Superior E may regain some of the consideration on the part of buyers that it has always deserved--unfortunately most will still go for a ~$300 OK-quality roof with a narrow field of view.
These days, I recommend the Nikon 8x30 EII to a lot of folks (I don't know what I'm going to do when the existing stock is sold out!). The EII is in practice, as good as the Superior E, as long as you don't find the slightly lower eye relief, the edge distortion in the wider field of view, slightly different ergonomics, or its slightly more delicate construction to be a serious problem. As for me, I consider it opticly to be in the same class as any of my best or most expensive binoculars. The $240 price is just icing on the cake.
I think the Nikon Superior E provide about as good a view as can be used by the human eye, so I don't see how anyone can assert that another model surpasses them for overall image quality (Incidentally, my glasses corrected vision is about 20/12, so I'm not saying this for lack of ability to see fine details!). There are plenty of top binos that are in the same league opticly as the Superior E, maybe even that better it on one optical parameter or another in the lab, but in terms of overall image quality I'm not convinced that it has been equaled. That said, the differences between top quality binoculars with regard to image quality are of ZERO significance for birding or any other practical use, no matter how demanding [I don't consider the gripes that are expressed on this forum (myself included) to be part of the real world--this place is a dimension to which we escape to pick at nits that are so small that we cannot agree even as to which is what or whether they exist!].
Getting back to my original point.... The way people write about how great the new models are, you might think that the differences they are talking about are something like I experienced with my succession of bino purchases up to the Zeiss 7x42 Classic, but mostly they're just excited by a new bino, or maybe it fits their preferences better than models they've tried in the past (so the improvements it offers them may have nothing to do with the fact that the model is new). Your Nikon 7x35 E is an excellent binocular, so you are starting your quest at a very high level. I hope that some day, there are binoculars with significantly better optics (I'd love to see a bino that is TRUELY sharp edge-to-edge!), but even then, the practical importance of such improvement would be miniscule. Unproblematic image stabilization technology would be a much bigger practical advance than higher optical quality. The big issue is ergonomics, including how easily/comfortably/quickly you can pop the bino up to your eyes and get a stupendous view of a bird. This is a major reason why we aren't all using image stabilized binoculars--so far, they are ergonomicly inferior. This is why I don't use the Superior E for birding--I don't have problems with blackout (as some people do with these models), but I prefer the handling of roofs, I don't like the stiff focus in the cold of the Superior E, and I like the way that my roofs hug my body when they are hanging from a neckstrap (which is always medium-width neoprene, from Op-Tech, I might add).
I don't think I'm any less obsessed with raw optical quality than anyone else on this forum, but when it comes to choosing a binocular to use from my collection of 30+ models (and, yes, I've tried many more models than I've bought! and no, I'm not rich, by "developed nation" standards anyway, far from it, actually), ergonomics is everything. Moral: Sure, try before you buy, but don't get so caught-up in testing minute optical differences that you don't give considerable (in fact, MOST of your) attention to the handling properties of the binocular. Even the aesthetics of a binocular are more important than the optics when you are choosing among top of the line models. How a binocular looks, how much you appreciate the details of its engineering, this is an important part of its ergonomic fit with your mind, and your ultimate, composite satisfaction with the instrument.
best wishes,
Alexis
PS. Wow, what a long note! I started this reply this morning, worked on different things all morning and afternoon, had my computer turned on and logged in to Birdforum the whole time, sat down and wrote another paragraph every now and again. It has really added up!
