Just went through a week of researching birding bins and was overwhelmed... way too much info out there! But, some of the feedback above is pretty good based on what I read. I purchased the Vortex Diamondback HD 8x42 yesterday at Cabela; store price was $239.99 but got a $30 discount using my Cabela credit card which brought it down to $209.99.
Why the Vortex? Almost every birding site reviewed it as one of the top bins with great optics, 396' FOV, 17mm eye relief, solid rubber coated body/metal (Monarch 5 is plastic) and the revised lenses have all the coatings and protection you need for being in the field. Warranty forever (except is stolen or you lose it) and transferable if sold. No receipt needed; if you have it they take care of it!
I examined the 10x42 Diamondback and the Vortex Viper 8x42 and found them just a tad larger, heavier; the Diamondback 8x42 felt good in hand and pretty easy to handle focusing, etc.
Just as a note: the Celestron Nature DX ED ($149 new on any sites) seemed to get some exceptional reviews for optics and general ease of use with some comparing it to many higher priced bins. The TrailSeeker is the upgraded version and at $289 more expensive but also gets great reviews.
The 8x42 Vortex Diamondback HD is a great compromise between cost and still gets super ratings for optics. The way to go?!