My first scope is still the one I use most. It is the Nikon Fieldscope 78ED with 30x WF eyepiece, coated in McNett camo form wrap. At the time (in early 1990s), I almost got a 60 mm scope, but when I saw how short and minimalist the Nikon was (especially compared to 80 mm scopes back then), I ended up getting it instead. My thought was that I could pack it almost as easily as a 60 mm scope but I'd have the advantage of larger exit pupil. I like the big bright easy view. Since then, I've acquired other excellent scopes, but I find my 78ED so handy that it is what I generally carry. Incidentally, in comparison to the Nikon 82ED, I prefer the position of the foot on the 78ED because it allows me to rest my focus hand on the tripod head and focus palm-up as if the scope were a big telephoto lens. I also find that the way I have my 82ED set up, with stay-on case and 30x DS eyepiece (which requires careful eye placement for best view), that it is an unnecessary hassle. Also, its extendable hood adds bulk without improving function most of the time.
My other most-used scope is a Nikon Fieldscope 50ED with 27x WF eyepiece with Quake Bushwacker objective cap and McNett wrap. I find that 50 + ~80 is a superb combo. If I could only have one? I'd go with ~80 mm because I don't carry a scope on all minimalist travel adventures or really long hikes, but I use one every day for car based travel and around my home area.
--AP