I have the Vortex Diamondback 12x50 - and I absolutely love them. I use these in the blind, so I can positively identify any bucks that I'm trying to evaluate. Heavy, but amazing clarity. Bought another set of the 10x42 and love those, too. So far, so good with them. You can buy a "demo" unit from Camera Land NY - for about $20-30 under the sales price (which is already a good deal)...and I got free shipping with mine. I called to ask what exactly what classified a "demo" - was told it was ones that had been set aside at gun shows/outdoor events to be be picked up and handled by customers. The ones I received looked like they have never even been touched. With Vortex's replacement policy, I figured it was worth a shot the first time around...bought a demo again without issues. Also bought a pair from BH once, when they had a super sale.
http://www.cameralandny.com/optics/vortex.pl?page=vortexdiamondback10x42I've had some Nikons that I really liked...can't recall the particular names on them though.
My advise is go to a store and try out a few that you like...and take them outside to check out at sunset...see how it looks in low light. That might be a difference maker in your decision. Then, shop online for the best deals...