I don't have a definitive favorite, but the Pokémon I do like tend to have a more feminine direction which unfortunately means I get stuck with having a bunch of degenerate waifu-fags as "acquaintances".
Gardevoir, Florges, Tsareena, F!Meowstic, Gothitelle, Milotic, Primarina, and Meloetta all come to mind in this regard. Hell, I even really like Jynx.
But my "exceptions" tend to be closer to a sure-fire "favorite". Venusaur, Honchkrow, Toxicroak, and Aegislash. Between this list and the last, I tend to flip flop on my favorite on the day you'd ask me.
But Venusaur and Florges would probably be my choice more often then most so run with that if you will.