I've always liked fire and electric types. I always take the fire starter and pretty much always get an electric type of some sort.
But there's nothing like a good ol' ghost/dark type. Being weak to nothing is pretty cool.

Agreed about dragons being over glorified. The only dragon that I actually like is Flygon, one of my absolute favourite pokemon.
Even then, his type isn't that good. Dragon/ground? Not the best, but whatever.