If the Kings were the fourth family, they would have my vote in a heart beat, but Freeside, not the Strip, is their domain.
Out of the remaining 3, I prefer the Chairmen. Not likely to eat you, unlike the course the White Glove society is back on, or the general creepy vibe they put off even if they were kind and wonderful people. And while Benny may have been an ass, the Chairmen are actually pretty cool about the whole thing.