Perhaps not the current group. But with the cure, he would be able to shape the second and third generation raiders (and while he may not live to see the third generation, Marie would likely take over his place).

Ashur.
I love FO:NV way more than FO3, but this one time I'll give FO3 the crown.
It nails the 'doing the wrong thing for the right reasons' target that the Legion missed.

It's just such a pity that the legion never got the quests and companions that would have let you see them in a positive light.

It's not really that Caesar is an [censored] (for me anyway, I mean hell House is basically an [censored] and so is Moore...now that I think of only YesMan wasn't..) but that his vision is so [censored]. "O I want to take over the ruins of a Pre War city so I can live in a fancy decaying tower of a dead robot-man." [censored].

I'm not sure that's what they intended. I think that the legion was supposed to be a group doing terrible things, but because they want a better world for everybody. Tough love, so to speak.
But because we never get to see (or even hear much about) the better world they have created in their own territory, the whole thing rings hollow.

He's actually made considerable progress, if you look at the average CW Raider. Once you get Uptown, you find out that a significant percentage of Ashur's Crew are ex-slaves who won thier freedom in the Arena...the story about only Gruber and a couple others doing it wasn't true. Slowly but surely he's taming them. The question is....will he have succeeded in making them manageable enough by the time he passes his crown to Marie for her to be able to keep control?

I don't think this phrase, "fleshed out" means what you think it does. Look at the amount of details available on Caesar's Legion and compare that to the amount of details available on the raiders of the Pitt. By any metric, the legion is more fleshed out than Ashur's band of raiders.

Now, you can think Ashur is more believable than Caesar, or nailed the whole "good person doing horrible things in the name of rebuilding society" angle better, but more fleshed out? No.

Personally, I think the Legion is a more interesting and intelligent antagonist faction than Ashur's raiders, though this really only comes up when you talk to Caesar and Ulysses to a lesser extent.