I like Fire. Who doesn't like Fire? Most of my teams tend to have Fire Pokemon on them, because there's nothing quite like incinerating your opponent's Pokemon to smoldering ash. Although, I think I've already used most of the Fire Pokemon I've actually wanted to train. Might be difficult to fill the spot in the future...well, I have a few more candidates. My Typhlosion from Gold was the first Pokemon I really bonded with, so it definitely has a special place in my heart, but my Chandelure was also simply amazing...this is why I'm not listing my favorites.
As I said yesterday, next is Poison.