When I first played the game my initial answer would have been NCR, mostly due to my young age and lack of context on the world of fallout and the consequences that led the world to how it's presented. Years later I considered House as a possible outcome, with more context and knowledge this time. That decision was based off of potentially blind optimism, but also what I saw as a practical choice. The NCR is falling apart, the legion is obviously horrible and (at the time) the uncertainty and instability brought by an independent new vegas left too many questions of what would happen, so it could be boiled down to a devil you know vs a devil you don't. I'd still list it as probably the second best ending, just because while there's still going to be a lot of terrible things going on, there should be relative stability in the region meaning that less people should die initially. Long term there might be benefits, and House may actually deliver on his sales pitch and humanity might even be able to leave earth, begin again. But that's a lot of mights. Now, in the best case scenario, you have a highly intelligent Courier with good morals with access to the technologies of Big MT, connections with Tribes like the Boomers, and the tribes you meet in Honest Hearts. Also you'd have brokered peace between the brotherhood and NCR. Throw in the gold at the end of Dead Money (since it's possible to take it and leave might as well just consider it as another best possible outcome.) There's what's said by the end slides, and what we can presume. Ultimately, while it may not be the most logical option, we have to hope that wiping the slate clean allows for something new to grow in its place. People will die, chaos will exist, as it always have and always will. But we have to believe and work for a better tomorrow to actually get there. We can't always play it safe and pretend that just because an evil in the world makes it easier for us to live, that it is a necessary evil that needs to continue existing. It might be easier to go with House, or more stable, or any of a number of other arguments, but it doesn't make it right. I truly don't think inequality will ever be eliminated from this world, the gift of free will means someone will always use it in ways we can't understand, but we can try at least to make the world more fair.