Mr. House, because it means that the NCR will cease to expand and Caesars Legion will fall into chaos, small wars being fought by dissenting legionaries over the land it has acquired. Much more interesting setting for future games in the region. I couldn't care less of the implications of House's rule, but it has a great effect on the rest of the world.
In that case it's either House or Independent, since independent has the same effect.
You right, though that kind of ending is a lot more interesting.