I won't deny many Pokemon draw me because of their appearances (i.e.: cute ones like Hitokage (Charmander), or cool/fearsome ones like Mewtwo), but ultimately it's their personalities, much of which comes from watching the anime. Pikachuu is very friendly and a true friend and companion. Hitokage is very loyal and innocent. Butterfree has a sweet personality and a heart of gold. Lizardon required work and time to trust and obey Satoshi, but afterward was a true companion and excellent fighter in more ways than one, and sought to improve himself more and more, even to the point of leaving Satoshi indefinitely to train with other Lizardon. Mewtwo was born by inappropriate means into an unfair world and desired to be understood and find his place in that world. Those are some good examples.