Its all personal preference really. with that said... i would go boars for pvp and pve till 50+
Since mobs dont last very long.. its nice that the boars charge in fast and you dont have to wait for them to start dpsing.

past 50 i would definitely get a little bit of variety.. the owl/bird screech is great for holding multiple mobs attention while you Mend Pet but they do not stack. So i would get 1 to 2 birds. Throw in a Coyote for Howl, maybe keep a boar for charge etc. Just try out a different mix of pets.