Honestly, if I had any power, I'd end up playing the Fen'Harel and screwing over both sides. I despise zealotry. It doesn't matter what form it takes.
Personally, though, I stand with the "reformed Circle" camp. Without the Circle, or some centralized system to train mages, you'd end up with a bunch of adolescent (and sometimes pre-adolescent) running around with no viable way of controlling their powers. Not everyone is going to have a trained mage living in their village. Mages, and especially Mage children, would become scapegoats for when something goes wrong, like if a village or farming community has a lean year, or if a number of livestock die from disease. We'd end up seeing the Thedosian version of the witch hunts within a short span of time. That, or the governments of each nation would press-gang any known mage into the military, to be used like human-shaped cannons.
And, yes, I know that happens with the Circle. The thing is, it usually only happens when there is a world-ending crisis going on, like a Blight.
The point I'm trying to make is that things do need to change. The current Circle and the current version of the Templar Order do not work. I'll probably stand with the mages when the time comes, though, because I will not reward the Templar Order for the past abuses that they have either ignored or actively covered up. But I hope I'll also be given the option to watch the mages, and express my displeasure that they're being lead by people like Fiona and Adrian.