This is an excellent question, one never asked. As you clearly have been an avid reader of Warcraft Hunter's Union, and no doubt a BM hunter, I need only remind you that you want to look for the Vapid Poopasaur that is a rare spawn in Silithus (it could be anywhere). It's kind of a waste of your time to come back here or to go anywhere else until you tame one.
Six months+ in and people still have to ask this question?
Pet damage was normalized; all ferocity pets do the same damage, all cunning pets do the same damage, all tenacity do the same damage. There's not much of a dps difference between cunning and ferocity (I've heard cunning even comes out on top sometimes), so basically if you're not herping around dpsing with a tenacity pet then pick whatever pet has a buff your group doesn't have or whichever pet is prettiest.
The thing I hate about forums is no matter who nice you ask a question or how well it is written or what ever it is about you always get made fun of.
The problem isn't how nice you ask it or well you write it, it's how easy it is to look up the answer by yourself. Every week there's a thread asking which pet is the best, which spec is the best, whether or not haste is better than mastery, and so on. I'm all for people looking for help if they need it, but seriously, read the stickies on the top of the hunter directory or google it. It's really not that hard.