I am at 31 so far. I have a Bulbasaur, an Ivysaur, two Venusaur, a Charmander, a Charmeleon, two Charizard, a normal Pikachu, a partyhat Pikachu, a Raichu, two Dratini, a Dragonair, two Dragonite, two Mareep, two Flaaffy, an Ampharos, a Makuhita, a Hariyama, an Aggron, a Meditite, a Medicham, a Wailmer, two Swablu, an Altaria, and just yesterday I caught a Kyogre.
I am probably most annoyed at not getting a Lugia - I did a lot of Lugia raids with zero luck - and I am baffled that I have not had a shiny magikarp given the absurdly high number of magikarp that I have caught since the shiny version was relesed.
Of the ones that I do have I would have to say that the Wailmer is my favorite - the alternate colour works really well - followed by the Kyogre.