I would suggest the Nvidia gtx 650 because it's better than the HD 7750 in Memory Bandwidth, Texel Rate and Pixel Rate. The only downside is that it needs a 6-pin power connector and a 400w power supply. If your power doesn't come with a 6--pin oyu can always buy a 4-pin to 6-pin power adapter, but they usually come with the graphics cards.
Source: http://www.hwcompare.com/13468/geforce-gtx-650-vs-radeon-hd-7750/