There was already a thread on this.... >_<
But as I've said, I like the sprite for the twins, because they are wearing pink and blue. And also the sprite for Super Nerd, because the robo-pikachu is cool.
With the Pokemon sprites, I like all of them that I've seen so far. It's nice to see something different though. But yeah, I don't really have a favorite yet, it's too soon to tell.