Only by going by Arena and Morrowind mecanics. And then it only applies the need of a trusty sidearm.
A overenchanted warrior could perhaps stand par with a powerfull mage(the spell resistance and the speed), but a battlemage would be able to push it even further(buffing upwards along with the enchants and spell pocket). But the pure mage, the magic level is just to huge to get over the gap.

The Adoring fan, even Dagon and Dagoth Ur are afraid of him!!!

Gortwog gro-Nagorm, and Divayth Fyr. Both pretty [censored], and Gortwog is a tactician on equal level of Tiber Septim, and quite a capable fighter. And Divayth Fyr is just amazing awesome. Also all of the original group of the Fighters Guild(The Skyffim) founded by the Tsaesci, because the snake people are like ninjas. Lightly armored, but fast and with quick deadly weapons.

Psijics for the win.
But we have a bunch of great warriors and mages a little here and there.

I heard he even annoyed the champion of cyrodiil to death

Nerevar was called back isn't he?

Called back? To the Dreamsleeve?

If it's regular people choosing it? Whoever'd be the most obviously available and whoever happens to be the most mythologized hero figure they got. Of course, the greatest warriors and mages are the ones who win battles before they even begun, they tend to be completely forgotten, leaving relatively sub-par folks to take the credit. Though since everyone remembers Zurin Arctus for saying this, and believing it true because they know him to be a great Battlemage, you gotta wonder how it all worked out for him. Hehe.

So in the more Imperial places they'd have Talos, since he's a deity and they have an entire Empire to remind them what a great warrior he is. Even the decline of the Empire is seen as the fault of unworthy heirs who failed to live up to his glory. For Morrowind, the Tribunal would be able to handle most everything, as they have in the past. Do they count as great warriors or as great mages or what?

I doubt they'd even really care if it was a mage, a warrior or a self proclaimed thief or a banker or a mudcrab or whatever doing it, so long as the crisis ended without their lives too destroyed. Hell, even a particularly charismatic person with little in the way of martial ability and a few good advisers could bring people together to avert a crisis effectively enough, through the intelligent use of lots and lots of poor militiamen and talentless hedgewizards.

Galerion, sure he was felled by Mannimarco but that was Mannimarco at his best, not the the sad remnant that took refuge in Cyrodiil.

As far as good mages go Galerion was the best.