Which to choose

Hi. i'm building a new budget gaming pc. here are my specs


CPU: i3 3220
PSU: 500W Corsair
Case: Fractal Design core 1000
MOBO: H77M LGA 1155
HDD: 500GB Western Digital Caviar Blue
RAM: PNY Optima MD4096KD3-1333 4GB
OS: Windows 7 Home Premium

Which GPU should I pick for gaming?

EVGA 01G-P4-3650-KR GeForce GTX 650 Ti or Sapphire Radeon HD 7770 Graphics Card

Games i want to play are: Minecraft, World of Tanks, Hawken, TF2, and maybe BF3 ALL ON AT LEAST MEDIUM. Don't care about ultra. just medium with decent frames. maybe low