When leveling, the only real question is: is there a pet of a certain family available at my current level?
Petopia site can tell you that.
And very very soon, just about any pet will be available for your level, be it sometimes rather hard to reach.
But for example: you won't be taming a porcupine anytime soon, even though it's not an exotic at all...
Petopia... best place to check levels and where it can be found.
As BM there is the additional bit about exotics: before you can tame exotics, the specc is a lot weaker.
So there the hunter level is important. More so than with MM or SV leveling in pvp I think.
Of course because of Bestial Wrath as a whole too of course, with any pet you use.