An excellent card. I had the 4gb asus 670 and its works very well. The nice thing too being that the 670 version is a 2 slot cooler rather than the 680 being a 3 slot cooler along with the 7950 and 7970 versions both being 3 slot as well. Runs very cool and quiet even at max load. Good as well if you want to overclock.
At 1080p resolution any of the cards will work good. I'd pick the cheapest of them. Going over 1080p if you want to stick with a single card then probably 7970 would be a good choice with the larger memory bus.