None. I dislike all the factions in New Vegas.
NCR is inefficient. As a game that takes place in the Mojave I make my decisions based on what I see in Mojave. Just because Shady Sands is a thriving community doesn't mean the Mojave will be better of under NCR. In fact the way I see it the only thing that will change under NCR control is the the Strip loses its glamor and Followers get sent away.
House cares only for himself. He claims that he wants to restore pre-war glory of Vegas but he just lights up the Strip and leaves it at that. Only a very, very small percentage of population gets something off it. House is a status quo candidate and will provide absolutely no change for the Mojave.
Legion is just horrible. Legion's ability to pass rule over next generations is dubious at best. The odds are that the Legion will become a warring warband after Caesar eventually dies, and will fight on and on until it just crumbles down. It might also fall into anarchy, who knows. The Legion is an entirely evil choice for a player that wants to mass murder folks just to feel the change. I'm not one of those. Plus I hate how Legion treats its women.
Independent is the most insecure faction. It has the most potential in making the Mojave a better place for its inhabitants but anarchy led by a barely sentient AI is not good when the Legion and NCR will eventually come back for revenge. I doubt that even the securitrons can maintain a two front war at worst. Independent is the best short-term faction, but who will take over when the Courier dies?
The Brotherhood is dying. There is not much to say in that. I would not want to live in the Brotherhood just to see it die because of ignorance.
Various town militas are not my choice since the pay is probably horrible and I will not gain anything by it. I think that militia stuff is a citizen's duty and everyone just takes guard duty from time to time. If I live somewhere I defend it but I won't deliberately join a militia somewhere.
Raiders and Criminals are a no-no by default.
That said the only faction I'd join as a GRUNT is NCR because I would have odds of becoming recommissioned to MP duty somewhere deep in California