The thing to remember with casters is that compared to their release versions they are all way, way more powerful. Mages are going to get all the glory but Wizards do bonkers amounts of damage (and have ports), Enchanters have amazing toolboxes, Necros do piles and piles of damage, Druids are pretty damned awesome, Shaman are awesome, and although Clerics are a bit on the boring side they too benefit from a host of little changes made over the years. Their spells all do tons more damage, they get Bash, you get rezzes right away, and their are a few crutch items floating about like -
Scales up to 51% at level 50.
Andfocus effects are in. Every caster not only has higher base damage today than they did at release but on top of that you've got effects like mana preservation (10% less costs) and the damage augments (20% more on dots with one, 20% more on nukes with another) and then of course the pet focuses. Pet focuses. Yow.
You basically can't pick a wrong caster in this environment. There isn't one. Wizard, Mage, Necro, Enchanter, Cleric, Druid, Shaman, or Bard it's all good stuff.
But oh man the rest of the roster. Between their relative power to casters and Monk fist damage (20 dmg 26 delay fists at level 50, wtf) there's just no reason to play a Paladin, Shadow Knight, Ranger, Warrior, or Rogue and there won't be for a long time.