It's actually a rather tricky question. The 765m is obviously faster than the 760m, but on the other hand it has to drive a somewhat higher-res screen. I don't know whether the extra grunt in the faster chip is able to offset the higher load.
Nvm I'm dumb; I misread the specs for the small one, and thought it had a 760 instead of the 750. The one with the bigger screen is the way to go, assumong you can carry it comfortably.