Pft my goth necro Unkind can do that :P. In this game there is no best due to you need to roll duck and cover constant. Hate to say this you can use any of them and do well, your best bet is to find which (you) and only you will like.
I would go Elementalist for a number of reasons.
1) Great support class for teaming with massive AOE damage, holds and heals.
2) When you learn to play your class and know when to switch between fire, air, water, stone or arcane you will own.
Start in stone, cast your sheild so you can round then all up, switch to air and cast a hold, dodge back and switch to water while their still held by your electrical field, cast your aoe to hold them all in ice while also damaging them, switch to fire (If they have any life left by then) and blast them with another AOE and rain a meteor shower down on them, if any come close, pick them off using the single target attacks, if you get hert, switch to water and heal yourself with water fountain for rain, but you mostly use healing rain to heal a group as its a big AOE heal.
You can do all this with a staff.
Or you can get up close and personal with 2 daggers and get another 16 different powers to pick from (I really like the fire sword or switch to air for the lightening whip).
Go Thief! My main in WoW was a feral druid. Thief all the way!! You don't get pigeonholed like people say, people DO need your AOE stealth skills. Stealthing in siege golems is hilarious; and I'm a lifesaver on the field, stacking my stealth aoes and cooldowns to rez somebody in the middle of an enemy zerg! You can build your thief a lot of different ways, but I'm built with lots of healing power, precision, toughness and condition damage - just because I can. They're more versatile than people think. I would say ele as well, but you CAN'T weapon swap, which pigeonholes you more than people would think; even if different elements do different things, I'm stuck between staff for support or dagger/dagger and i can't swap between them fast enough in combat.