There's actually quite a difference between cards in any series.
1) Quality
2) Noise (cooler)
3) GPU frequency
4) Overclocking capability
5) VRAM amount
The card I recommend is from Gigabyte:
http://pcpartpicker.com/part/gigabyte-video-card-gvr927xoc4gd
Normally I don't recommend 4GB of VRAM at this level of performance, but it's not adding very much to the price of this card. The 2GB version is about $250 so that's only $20 more.
It might benefit in the future if you Crossfire, or in certain games like Skyrim currently with Mods, or just add to the resale price.