Well title basically says it all, price doesn't matter, performance wise, which is better and why?
P.S. If you happen to know if the R7 265 for a fact is compatible with the Dell Inspiron 660 slim (I will be getting a bigger box, physical size isn't a problem, neither is the PSU) please say something, don't wanna buy it if it ends up being better than the 750 and end up with an overpriced paperweight. If you don't, you don't have to answer this part.
P.S. If you happen to know if the R7 265 for a fact is compatible with the Dell Inspiron 660 slim (I will be getting a bigger box, physical size isn't a problem, neither is the PSU) please say something, don't wanna buy it if it ends up being better than the 750 and end up with an overpriced paperweight. If you don't, you don't have to answer this part.