Suggestions on an alt with utility?

[RipVanFish]

Utility as in providing a service such as porting, exp resurrections etc. I want to level an alt but want it to provide utility/service, I only have the time really to have one “main” class (a mage) that I can take to 50/60.

The alt class would ideally be beneficial at lower levels, e.g. druids can port folks in their mid levels.

What do you guys suggest for an alt that will be valuable to have, without necessarily ever reaching 50/60?