I can't vote! Too tough decision between balance and ele.
I'm thinking in a bg/rbg/1v1/2v2 situation here btw.
They have the off healing, the escapes (boomkins, at least), the utility (healing tide, healing stream, solar beam, vortex, defenses, knockbacks, grounding, tremor, symbiosis, roots) and last but not least damage.
I find their damage to be high yet unpredictable, with 80k + 80k lava bursts and 100k+ starsurges. Maybe its possible to live through the damage, but the healing they pump out at the same time is almost insulting
I can't forget WW monks either. Up your ass all the time, offhealing, roots, stuns, annoying tiger, interupts, their own trinket, and should all else fail, run away like a rogue. Jesus. Im sure there's something I havent mentioned too.
For reference I play a destro lock. Because real men cast chaos bolts and gets rejected from random RBG groups because "affli is much better" :| meh