Do casters reign supreme? Or is it just pretty much everyone kicking ass in their own way?
I'd say both. The casters do achieve a level of power that is quite unrivaled by other classes. Particularly, their ability to choose any spell from any school makes them quite versatile. However, contrary to D&D, the casters do not necessarily become better than true specialists. I'll take an example: Invisibility allows a Mage to kick the crap out of any Sneak specialist ... unless they have the Ghost feat chain. Same about damage spells, they become dangerous enough to beat any average to good fighter. However, a real battle specialist like a Soldier will definitely be the
threat on the battlefield. Lastly, Charm Person V is devastating as a social ability, but a good Assassin or Courtier will have abilities that get even more efficient than that.
So that would be my opinion. The Mage is supreme because of its sheer versatility, an issue I've raised several times and for which I now have a satisfying solution (limited disciplines at Level 1, possibility to get more instead of a Spellcasting or Skill feat). The Priest works fine, extremely fine even. I insist that it is the best class-innovation of Fantasy Craft. But, as I said first, everyone is kicking ass. That's the real important thing in my opinion. Everyone has a chance to shine, I've witnessed it every time, and the gambreakers (level 14 abilities) are helping a lot.
I would add a last remark to this. As Psion said, Spellbound is about to be released. But even without it, magic is conditioned by campaign qualities a lot
. So first, it doesn't have to exist if you don't want to (you can replace it with miracles
altogether, which wouldn't be a bad idea in my opinion). Second, even if it does exist, "default" magic is just that: default. It doesn't have any limitations, specificities, so that it fits any character concept and campaign. But there is a real chance that, in your campaign, magic isn't that
easy. Well, that's when campaign qualities enter play, and they can significantly shift the balance of power, making the Mage more equal to its peers.