I find Arcane extremely satisfying to play in dungeons, Arcane Barrage spam when you get 4-5 procs in a row gives a big chunk of dopamine, but it’s only worth on forti weeks IMO, tyrannical as Arcane is boring af.
Fire is underwhelming and I find it the most annoying Mage spec.
So my vote goes for Frost since it’s the “safe pick” in most scenarios, good damage, good mobility and the tankiest of the 3 specs.
All classes and specs are pretty balanced right now with a few exceptions. Some do more? yes, but Frost’s damage is competitive so that shouldn’t be a concern, is what I meant.
Your main rotation consists of Flurry, Ice Lance, Comet Storm, Frozen Orb, Cone of Cold, and buffed Blizzards which are all instant casts so I’d say that’s pretty mobile.
The only thing you really hard cast is Glacial Spike and you have Shimmer/Ice floes to move away if anything happens.
Double Ice block, barrier reset, and more slows/roots than any other spec in case you have to kite.