Mewtwo because he was the first "god like" Pokemon in the franchise. He was stupidly strong, and plus his Shadow Ball attack reminded me of a Kamehameha attack. He's still my favorite to this day.
I agree with lise123, Being able to view the characters and listen to their lines, and having those in-depth character profiles I miss, and going back to the basics of what made SC fun would probably help it a lot. SC2 got a perfect rating, I don't recall any other SC game getting a perfect...