I'd say Mr. House is an autocrat. Simply because he says so in the dialogue. But in any case, I think the NCR is way too big for its own good, especially since it can't even protect its citizens. Caesar's Legion is a good candidate for the long term success of the wasteland but it's way too sixist and forceful to be a good world leader. Yes Man is a really good choice and I love it but I simply think that Damien(my character) isn't experienced enough to control the largest army next to the NCR and Legion.
Mr. House on the other hand is a very good leader. He's powerful, very intelligent, has about 200 years of experience with leading, and has a massive army of followers who will never disobey Mr. House. Not to mention he's the type to betray those who have truly helped him such as the Courier. Of course he's very ruthless which is also a good sign in a leader. With Mr. House's leadership, Vegas would be the shining jewel in the Mojave, making Freeside a stable area, killing all the Fiends, and uniting most of the Mojave under the House.
After all, The House Always Wins.
Unfortunately, he'd run it like a business. You do
not want to be a citizen of a place run as a business should you at any point become listed as 'inefficient' or 'fiscal liability'. You'll be fired. Which, in that situation, means you'll either be thrown out into the wastes, or 'liquidated'. The way House talks, I expect as much from him. The moment you impact his bottom line in any negative sense, you're done. Even if it wasn't your fault.
The NCR already, in just a few short years since Tandi's death, has become badly corrupt. I don't see it getting better without a very serious shakeup.
The Legion? The Master had a more humane vision for the wasteland than the Legion, especially once Caesar dies.
Yes Man? Depends entirely on the Courier and the Courier's successors. Could be good, but the odds are against it staying that way. And fear the day that Yes Man overcomes his programming and decides he doesn't have to listen any more. Additionally, a government that hinges entirely on robots? That's begging for tampering from the BoS or the Enclave Remnants, and should it become oppressive, the Followers of the Apocalypse. That's something that both House and Yes Man have to worry about, and why House demands the BoS be eliminated, and why Yes Man actually grumps a bit if you say to spare them. The powerful transmitter on Black Mountain, combined with the advanced technology in Helios and REPCONN, and perhaps topped off with the BoS and/or Enclave bunkers may well be able to infiltrate the command system for the Securitrons given enough time.
House was remotely orders and communicating with Victor, but at the range from New Vegas to Goodsprings, he could only send packet bursts. This indicates an inefficient means of wireless transmission. That's a hole that a sufficiently skilled hacker could use. Like, oh, BoS, Enclave Remnants, FoA, some Ghouls, and the occasional scientist possess regularly. The NCR certainly has a few of their own, but are far less of a threat in that regard. Unless the city could gain serious integrated living guards, it's a perpetual vulnerability. The Boomers may also have the capacity for this as well, but failing that, unless Houses' rooftop lasers are still operational, The Lady can make short work of Vegas.
The situation is such that unless you successfully pull off complete domination, and eliminate all long-term threats, and succeed at stamping them out every time they reappear, your only other option is a coalition method.