1 week ago (Pre-release)
I'm going Orc so I'll start off with a boar. If I find myself ahead of the pack I'll stick with the boar as it is easy/cheap to feed and I like the charge. I'll use my head start to camp Brokentooth and get it early.
If I lose my headstart and find myself in the middle of the pack. PvP will be an issue and I wont be getting Brokentooth until after I hit 60 because I have fallen behind, at which point I'll be grabbing any other cat to level me to 60.
Of course at 60 I'll be picking up my obligatory Blood Axe Worg for max rank furious howl and bite. With Lupos shadow damage likely being out, this will be the required entry level raiding pet for hunts (a wolf with howl) in most guilds.
As a general leveling pet on a pvp server I would recommend cat. The combination of attack speed for spell pushback, the balanced stats, prowl and dash make this a generally good choice.
As a general leveling pet for pve or if you are ahead of the pack on a pvp server, I would simply stick with an owl or boar to get you to Brokentooth. The wait time for Brokentooth will be brutal... It is worth sacrificing your lead and waiting early if you can. "Yay I hit 60 first on my server... Now to go wait for Brokentooth for 3-4 days..." VS "Yay there are only two other horde players in the Barrens, I think I made it here early, I'll camp Brokentooth for 4-6 hours and grab him."
After leveling a few hunters to 60 on private and one in retail vanilla, this is my general take away. Just my 2 cents.