Radeon R7 265 is much better because it has 256bit
u may check the following specs of both card which u can decide
Radeon R7 265 vs Nvidia GeForce GTX 750
Higher pixel rate 28.8 GPixel/s vs 16.32 GPixel/s More than 75% higher pixel rate
More render output processors 32 vs 16 Twice as many render output processors
Wider memory bus 256 bit vs 128 bit 2x wider memory bus
More shading units 1,024 vs 640 384 more shading units
More texture mapping units 64 vs 40 24 more texture mapping units
Higher clock speed 1,020 MHz vs 900 MHz Around 15% higher clock speed
Significantly higher turbo clock speed 1,085 MHz vs 925 MHz More than 15% higher turbo clock speed
Higher texture rate 82.64 GTexel/s vs 57.6 GTexel/s Around 45% higher texture rate
Higher memory clock speed 1,502 MHz vs 1,400 MHz More than 5% higher memory clock speed
hopefullly this would help u at lot