This is the question of the week as I've been trying to decide how I feel about Moats for my own potential waiver moves too. The only thing I can say is that Moats was involved in 30 of the Texans 69 offensive plays last game, and that's probably a reliable indicator of how they plan to use him, more so than the 3 TD game the week before.
Where that makes him stand against the other options also depends how you rate them. I love Betts, for example, but I don't think Washington is going to be in the position to run the ball in a lot of games the rest of the way. And Charles I'm really down on, because I don't buy that Kolby Smith isn't in competition with him for touches plus the Chiefs have only scored 1 TD on the ground since Dec. 2008.
Long story short, for me that list goes: Forsett, Moats, Betts, Charles, McFadden.
Unquestionably, there are others who'd have it more like: Charles, Forsett, Betts, Moats, McFadden.
Best of luck however you go!