Mages and Warlocks are fairly interchangeable.

Desto/Frost offer replenishment.
Warlocks get you bonus spell damage.

Mages have food/water and portals, and mage Heroism/Bloodlust.
Warlocks have health cookies, soul stones, summoning and water breathing, plus whatever pet perk you want to have.

Mages can polymorph humanoids and beasts.
Warlocks can seduce humanoids, banish elementals/demons and play with fear.

Damage is close enough that neither is that far ahead/behind.