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.
I'm doing 2150MH per 750TI at default clocks speeds on my Gigabyte 750tis right now. Chris and Chris have said they have a version doing 2.8MH that will be released soon. They also have a new version of Groestl that is far better also, but no eta on that one. I can't wait to see what they can do with higher end Maxwell cards that will be released later in the year.
Remember this cheap $150ish 750ti card competes with 270x on price but eats 290x on performance which is utterly fantastic (if you own a few of them)!

I'm about split 50/50 on AMD and nVidia at the moment but I'm not buying any more AMD GPUs at present.
Makes me want to sell off my AMD cards and replace them with Maxwell cards. The downside however is that ccminer isn't as "polished" as cgminer or variations of it from an interface or API standpoint. Maybe one day when they get bored with new algos they will work on these things.
C&C are really ringing out the performance of the Maxwell 750ti cards. I'm sure that more could be done on some algos for the AMD side of things if the right person/people were involved.