Depends overal in the game arcane pets are gonna be the go to pets but you want to look for a pet that boosts int mainly and then strength secondly for best stats for mage. Of course the majority of pets in the game are good it just depends on what you are wanting to do such as farm elite maps, farm gold, pvp, or pve. So I would say there is no “best” pet for mage there are good pets though.