This question pulls quite a lot from Brian Ballsun-Stanton's paper on constrained optimisation (i.e. making your character awesome), so that might be a good thing to read. I know that in D&D ...
There are many Leader role classes in D&D4.0 these days. Cleric Warlord Bard Shaman etc Which one makes the most effective healer by the numbers? Numbers to be evaluated Hit points healed ...