Depends: for premades gnome mage, cause holy paladins enable them a lot and shamans are very easy to cc and kill in group pvp.
In world pvp, 1v1, small scale pvp, undead anytime: elemental shamans are a pain in the azz for mages (big time) although they’re not a hard counter, and fear is your number 1 enemy as a mage.
Wotf won’t stop a warlock from killing you unless they are learning the game Wotf is really good on rogue but irrelevant on the rest (warlock perspective). Also game’s horde favoured, mostly by the community, so if you wanna be a better player eventually roll alliance. Gnome is also mathematically better, and as mage you don’t even need to deal with annoying stuff like wotf or tremor like we do (sorry, got absolutely zero respect for horde warlocks, thats just easymode until BGs)
every pure caster will do well as a gnome.
more intelect is good for everyone.
Escape artist has applications everywhere.
A smaller hitbox means it will be harder to be hit by enemy melee players.
Will of the forshaken is great for melee classes who want to kick the snot out of warlocks, priests and maybe warriors. It can be replaced for alliance by dwarven priests casting fear wards