brand correlates with build and cooler quality along with customer service quality in my case.
for your budget, you got a good deal of choice to pick from the GTX660, GTX660ti, 7870, 7950, or a 7970/GTX670, with the right deal. granted, the 7950/7970/660ti/670 are overkill for WoW, but i guess you can try to future-proof it for future expansions.http://www.techpowerup.com/reviews/AMD/Catalyst_12.11_Performance/20.html
note as well, 7950s & 7970s currently come with 3 free games. maybe you're not a fan, but who knows? maybe you'll have a use for them.http://www.newegg.com/Product/Product.aspx?Item=N82E16814202006