Templars. One, because their missions is actually a lot more fun having like three different parts instead of only one going into the future.
Second, I believe the templars need a fist around the mages enough so they don't move, but enough for them to squirm comfortably. Why? Because magic is literally the power of creation and life in this game. Suddenly generating energy in the forms of fire or shields, manipulating people's thoughts or their very body movements. They make the blood in their foes veins work against them. This is a horrific power. A power only few can actually have at the moment. Revival of the dead and the actual changing of matter are not laughing matters.
Third, power corrupts. Absolute power corrupts absolutely. There's always going to be something that a mage might feel not powerful against. Something to keep reaching for more power against, wither it be demons or actual templars. Wither through fear, pride, or desperation they will attempt for it. The outcomes have always been horrible.
Considering i've sided with the mages in both other DA's though, kinda makes me a hypocrite. But I still stand by the fact that templars are completely needed.