Ncr is the best, as it allows the last, best hope of rebuilding humanity to thrive in un radiated lands with electricity for everyone.
Thats more like the worst ending i mean Mr House will send people into space like mass effect.
Depends what you want. The endings represent a sliding scale of total anarchy to dictatorial order. The NCR ending works out the best for the most people (if you do the sidequests right) while the Legion ending sees most of the smaller groups wiped out or enslaved. Mr. House assumes dictatorial control (and is an abomination who lives in a tube and thinks everyone's expendable) but apparently he'll let you play Mass Effect, or so a fellow with no commas tells me. There's a wiki page that describes all the endings in detail, I'd check there and see what works for you.