Ironically combat medics are one of the strongest healers out there, but like just about all classes in this game doesn't really become good until much later in the game.
By "strongest healers" I suppose you mean difficult to kill, because with supercharged cell and the shield you are more or less god-like.
Commando/Mercenary healers still don't stack up when compared to Sage/Sorcerer healers though.
All that aside, I enjoy my Merc healer very much. I can effectively keep a small group alive in PVP and not get myself killed (so long as they keep people off of me).