The benefit of having a combat pet in my opinion is that they can pull from a longer distance than any other method. The pets do not do that much damage overall. The 'pokemon' achievement pet (rocknose) actually can block spell casts as well as do damage and pull mobs, so I tend to use that one the most.

That being said...tigers are a bit faster than other swift mounts when I've tested them out, the faction tiger comes in three 'colors' and its the only pet that does a hide mode which is very nice if you get stuck on a ress pad with a lot of people blocking you (cough cough wbwbwbwb) and it does a bit of damage too if you use it for fighting.

On a demo you can fight with tiger and cast most spells. Finestkind.