Best hunter leveling pet?

[Asics]

Sporebat for obvious reasons.

[Shawaam]

The best one would be a spirit beast due to them having a heal for you. Though, since they aren't aviable untill level 70 and only for BM, go for a tenacity pet with a root/slow. The damage loss against a ferocity pet at low level is non-existant.

[Dch48]

Pretty much what everyone else said with one exception:

When you get to the 83-84 levels, you'll definitely want a tenacity pet. When cata first came out, I leveled my hunter first and once I hit twilight highlands my spirit beasts were getting wrecked on just two mobs; brought out the Rhino and breezed through it. Highly suggest a tenacity pet for any spec once you get out there

I've never used anything but a ferocity pet and never had a problem with any mobs at any level. Tenacity pets are highly overrated.

[Maelstrom51]

Cat for questing, wolf for dungeons. The reasoning behind this is because cats have the largest buff for hunters, but its already covered most of the time for dungeons, and 5% crit is the next best.
Tenacity pets are useless - you'll kill things too quickly for their slightly better tanking ability to matter. In fact, if you're leveling as Marksman, mobs will probably be dead before your pet even reaches the mob.

[Delaios]

A tenacity pet. Thunderstomp stops your mend pet pulling agro. I used a gorilla personally for the looks, but a bear or turtle would probably be the best.

I´ve got plenty of experience in pulling big packs when soloing, and Thunderstomp does next to nothing to prevent Mend Pet aggro. The aggro from it is barely enough to last two ticks (that's when the "High aggro" warnings start to pop up. The only way to get proper AoE threat on your pet is by misdirecting a few Multishots onto it.

On topic:
A cat is best for your everyday levelling and questing, followed by a wolf. A turtle/beetle is best for dealing with elites and group quests. Because pets level with you automatically when you call them, there's little reason to not tame a cat and turtle/beetle.

[lurialus]

Yes yes, my post was replying to the suggestion that you macro pet MD into shots, which is counterproductive when you want to actually USE those shots midfight.

And i was suggesting macro'ing it to a shot, most likely the opener (SrS for example) so that you dont have to have it on your bars, and it means you can be a lot lazier. I'm still not sure why you would think that is a bad thing.

[Maelstrom51]

MD uses a global cooldown, and preferably should only be used before a fight starts.

And as far as macroing it with Serpent Sting for leveling....why would you ever do that? You shouldn't even be using Serpent Sting while leveling, things die far too quickly to make it worthwhile.