You should try Holy Priest and if Smiting foes to a slow, very, very slow death doesn’t sound exciting, then you can strap on your Disc Priest boots and try hurting to heal, it’s fun and OP atm and bunches quicker than Holy. I’m a Holy fan though as I enjoy the suffering DPSing on a healer brings with it. 
Also everyone should have a Hunter, just for farming etc, pets collect loot, it’s a Netflix and farm situation, you know all of this already though, so just typing out of habit now.
Basically you need a ranged toon, something very different from a DK.