Wizzards level up faster, they do AOE kill where a warlock is running around.
But in PVP and wars, warlocks are ways better. Wizzies are real weaklings, I'm sure that I'll manage it to have my level 77 wizzard killed by a couple of movias.
Wizzards are very good at hunting because of the mass NPC thief killing, they can't stand high level thieves and they are champs in levelling other players up.
So as usual there are pros and cons, it depends of what you ask of your build.
