In all honesty, most AMD graphics cards are pretty much the same in terms of hardware regardless of manufacture, so really it comes down to service like warranty and extra goodies. I would personally go with Sapphire or XFX. If you're looking around the low $200 range for a video card look at either a 5870 or 6870. From what I've seen 5870s are slightly faster, but are slightly more expensive and consume more power and release more heat than the 5870s.
Newegg.com - XFX HD-587X-ZNFC Radeon HD 5870 1GB 256-bit DDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity
seems like a good choice after rebate.
The 6870s on Newegg are almost all equally priced, so just search there and find one you like.
If you end up getting a crossfire motherboard you should be able to get another later on down the road when they get even cheaper.