I always do 42-6, but, like all the other quests, it only gives you 0-3 Star Stones. To be honest, the crisis quests is the only way to get a decent amount. I think the chances for lower quests is miserable, so don't go there lol.
Edit: I believe the Boss Battles and/or Challenge Quests give out ~7? But since it has a long cd, I dunno if it's worth it... never tried them.