NCR.
Wild Card is stupid, essentially for those who either don't care or kick the can down the road. You throw your hands up and walk away one way or another.
House is assuming he is what he says he is, instead of a madman with akin to the model plane maker in Flight of the Phoenix. His plan to leave Earth behind to eventually seek a new planet to settle his choice slice of Mankind is one indication of that. All you have is his promise when he's ultimately the only one in control.
Caesar's Legion is arbitrary and prone to collapse violently in the near future. It'll be a glimmer of civilization before returning to the barbarity. Caesar without cancer might have a chance, but I think his ego over inflates his degree of real influence, that the Legion will civil when their society revels in savagery. People like to overrate the influence of leaders and ignore the literal will of the people, not the nice, sensible way people like to think of, but the lynch mob demanding their will be done and if a leader ignores them they'll find another one, often violently.
NCR at least has the rule of law and last sliver of Western Civilization left.
I do find many comments here funny about it expanding and collapsing. All nations fall, what's as important as what a nation does is what they leave behind, especially in a world like Fallouts. NCR will fall, but it'll leave behind fragments of similar nations seeking to grow and build in a sane, evolutionary way, not a revolutionary one as every Fallout antagonist has pushed. That theme may or may not be intended, but does highlight how much the NCR is a faction, even inl NV, like the BoS, they do not seek to turn world upside down overnight while those that threatened the world seek to "fix" the mistakes of the past in various, radical methods (ignoring the issue that they cannot fix the human condition, Ron Perlman's opening phrase isn't touched upon in game much, but it underlines the fundamental driving force, past, present and future) largely driven by one individual, the only exception being the Enclave, though that depends on the difference between their leadership and their common people).
IMO, the only problem with the NCR is that it's entirely too much of a carbon copy of the US, that it went from a tribal backwater village to an anachronism in a matter of generation, not a cargo cult civilization of tribals poorly imitating the US their a mirror darkly and mythologizing a lot of it more like the Chosen Ones village was like.
I also think a lot of the problem with many posters comments here is that they hold the same ultimately progressive, positivist position as those in-game that try to "fix" things, you cannot and you never will, there'll never be an optimal solution that'll prevent Mankind from repeating the same mistakes, and by seeking that goal, you are unwittingly playing into the cycle while only making it worse. The NCR is the one faction that has never sought that end, they simply want to do what they want and if the future goes badly, they'll fade away like everyone else, like every culture has thought like including ours, despite our neuritic worrying otherwise.
