Mage
+ Can conjurer food and drinks
+ Self Teleport to cities and make portals for others
+ Excellent crowd control (Polymorth, Frost Nova)
+ Frost spells to slow down or Frostbite freeze things in place when it procs.
- Very fragile, you have to put up Ice Barrier if you know your going to get hit but if you don't like being jumped by a Rogue then your screwed.
- Use of Frost Nova requires practice, I have used it before in PvP and used the spell too early, sending me to the grave.

Warlock
+ Can summon Demons and with the Voidwalker they have a much better and easier solo experience.
+ Can apply a Soul Stone to self-resurrect themselves or others.
+ Can soak up more hits than a Mage can with more Stamina.
Can't really think of negatives about Warlocks at the moment, maybe someone could refresh my memory.