SCH. The fairy is unreliable and needs macros to work properly, SCH has crappy aoe healing outside of cooldowns and the shields are unpredictable. I just don't find it comfortable to heal with in any way and on top of this it has the most unthreatening weapon type in the game. If it wasn't for SMN I still would not have leveled SCH to max. The runner up is MCH. Unpredictable, low damage, no damage support, lame animations and you have to keep summoning the turret in dungeons. At least BRD is fun at level 50.