Which type of Pokemon is your favorite? My vote goes to water. It's only weak to electric and grass, which aren't very common attack types anyway. Most water types pack some type of ice move to handle grass types as well. Water Pokemon also range in uses, from the physical threat Gyarados, the bulky vaporeon, or the speedy special attacker Starmie. They also benefit greatly from rain.

Water attacks take care of rock, ground, and fire types, while the ice attacks they usually pack can take care of dragons, flyers, and grass types.

Not to mention the STAB moves they have are all useful. Surf does a good amount of damage, Hydro Pump can give you that extra punch when you need it, Waterfall can net you some flinch hacks, and Scald can make a physical threat damn near useless.

...So what's your favorite type?