Originally Posted by
squidbear
Affliction is the number one PvE spec, in terms of average damage and highest damage. most players use Affliction because of this however, skewing the results by way of representation. competitive Affliction PvP is severely gimped however, any damage potential requires use of Haunt and Malefic Grasp spam, eating shards and all but guaranteeing you a Shadow lockout unless you are incredibly adept at juking.
Demonology is the best all round PvP spec, the trinket/dark soul/metamorphosis = huge Chaos Wave crit playstyle was nerfed, but Demo is still strong with strong pets, Imp Swarm for quick fury generation/mini-burst, nice mobility (5.2 removes double teleport however), a knockback, barely any casted spells (instant dots, pets, cooldowns, fel flame as filler and touch of chaos in meta) and has the best synergy with Grimoire of Service which is a really great utility spell for high-skillcapped players. Demo is decent in PvE, nice for movement, burst, and AoE fights, but ultimately behind Affliction.
Destro is a blast in both PvE and PvP. it sims lower than Affliction and Destro, and ranks probably on a par with Demo on average. its strengths are cleave fights, and fights where you can Havoc/Shadowburn snipe for insane damage and ember generation, but does not perform so well on single target. in PvP, you will have an absolute bomb using this in PuG battlegrounds and low rated arenas, one/two shotting players with Havoc and Chaos Bolt under Dark Soul. however, once you begin to approach competitive arena it requires an extremely skilled player to get any unmitigated Chaos Bolt casts off and it can be an extremely frustrating spec to play, which is why most high ranked players use Demonology.