Still though, that's more of a clean up job they did on Shinra. Sephiroth and the Weapons pretty much did most of that leg work themselves regardless of Avalanche's involvement. Not saying this is a strike against FF VII or anything, really the whole point of Avalanche was a plot device to get things rolling rather then be the main focus of the story anyway.

And yeah, Returners may have accomplished more of their goal by comparison to Avalanche, but oddly they kind of ended in failure once Kefka made the world go boom.

So yeah, FF II is, at the very least, the only indisputably successful FF Rebel group.