Building my first PC

From the benchmarks I've seen, they go toe-to-toe with each others.

This Sapphire Dual X 280X is a bit cheaper than the ones you have listed.

http://www.newegg.com/Product/Product.aspx?Item=N82E16814202046&clickid=RomxpTU6oRWtRVi1A8SiszfIUkTT1cwmBxUEwI0&iradid=97618&ircid=2106&irpid=79301&nm_mc=AFC-IR&cm_mmc=AFC-IR-_-na-_-na-_-na