A 750 ti is roughly 20% faster and uses significantly less power. If they're similar in price, it's the 750 ti no question. However, you can get an r9 270 for $20 more than the 750 ti superclocked, which is a better deal if you're not worried about the extra power. It's all about your preference, but the hd 7790 or r7 260X is outclassed here.