Hotbot is
Spriest with zerking + 3 orbs + specced into twisted faith ---> Mindblast
Thats just Mathemagix that hits hard...not mages in general
it rolls like this, if you wish to do damage: shadow priest > disc priest > frost mage > arcane mage > affliction warlock. (this is based on a pug where you do not suck.)
if you are looking for high crits, boomkin > shadow > frost mage > ?
I honestly wouldn't put arcane mage behind frost mage for sure and probably disc priest too for damage. Frost mages are mainly played for CC and disc priest don't have the damage boost that spriests get