mined X11 Nvdia is better than AMD?
Yes. The 750Ti can get 1.8-2mh or even more on X11 for only 50-60 watts. On scrypt it did between 300-400kh. That is 5-6x the scrypt mining rate. My R9 290s do 2.47mh on X11 which is roughly 2.9x what it got for scrypt mining and it uses ~180 watts per card.
Basically the 750Ti is 3x as efficient as the R9 290 at current X11 mining rates and power consumption for those cards.