I've done two groups of hunters to 60 and my mother just got done leveling a hunter duo to 60 as well. BM all the way. With just two, you could probably get away with MM or SV for some better DPS on both but my opinion on it is:

  • when you really really need DPS, you won't be able to blow enough cooldowns to live long enough to do what you were trying to do (over-aggroing the pet, etc.)
  • when you can't DPS enough to do it, two BM pets with mend pet glyphs can just outlast it.