Is it cheating to say Arcanine? (it is the legendary pokemon after all). If it is... then I'll say Lugia - because I loved the 2nd movie, it always felt special in the games (like it was the first 4 type pokemon - psychic, water, dragon, flying). Also its made me a lot of money (selling my old pokemon cards, picked up a PSA 10 lugia not that long ago for £190 and people are offering £600 for it).