Best hunter pet for tanking is Pig as mentioned. While Turtle has damage mitigation its slow, and lacks the skills to generate agro from damage, probably the main reason they are rare beyond about 30.

Ravagers are best DPS, when my hunters get to 70, I'm going to split the pets (currently have a ghost saber and a bellygrub each) and have one tanking with a pig and the other dps with a ravager...

But as a duo I won't be doing instances unless I out level them