I'd go Marks and get Go for the Throat right off the bat, and then dump full Beast.

I've done two different leveling specs Beast and Marks. And beast is by far the funnest/fastest/Safest. But go for the throat will help alot with all the new pet abilities.

Any tenacity pet will tank nicely with thunderstomp. I liked bears because they had the AoE swipe ability which was nice. The bird screech was okay, but it didnt do dmg so after it wore off the extra mobs would come after hunter.