I personally like Moeen, and think he'll do better than Rashid in the UAE, purely because Rashid bowls too slowly. If we saw anything last time England went to the UAE, he faster your spinner bowls, the better they do there, as the pitches do seem to facilitate quick turn. Ajmal was all over England (some of the was down to him throwing it enormously) but a fair bit of it was down to the pace he bowled.
Ali is learning quickly, and has picked up plenty of wickets without really playing on any spin friendly surfaces, and hence he's gotten his wickets through the length he's bowled and a small amount of turn.