Those two units aren't really comparable, so don't know why you've narrowed it down to those two.
The EVGA SuperNOVA NEX750G Gold hasn't been reviewed yet. I have heard that it is supposed to be a modified FSP Aurum. Which usually isn't very good @ 750W; it is group regulated, ripple and noise gets above 50mV at full load, noisy/fast fan, even in idle. 80 Plus Gold efficiency is about the only good thing about it. Hopefully EVGA have polished it into a gem, but until it has been reviewed no one knows what it's like.
The Corsair TX850M is indy regulated, 80 Plus Bronze. Again the ripple and noise isn't so good on full load.