The card I currently own is a MSi GTX660 Ti Power Edition and im loving it. Costed about $300. Although if your not looking for the Nvidia technologies like PhysX then the AMD card menstioned above will give you great bang for the buck.
The 7950 is the best one, or the 660 Ti is slightly worse but has PhysX. Go with MSI, Gigabyte, Saphire, or eVGA (Saphire is a AMD only, Evga is nvidia only).