Most popular hunter pets according to Petopia
No, they don't have precise stats from the game, but Mania does let us know what the most visited pages on Petopia are -- and considering Petopia is the definitive resource for Hunter pets available on the internet, I'd say that their data has value. While Mania doesn't give us a full listing of pets, he tells us that the most-visited pet page belongs to the Ghost Saber and that the number two spot belongs to the game's only black lion, Humar the Pridelord. And the award for least-popular pet? It looks like that goes to the Webwood Lurker in Teldrassil. (And now I'm tempted to go tame one just so they won't be so lonely.)