If pokemon was more 'real-timey' combat wise, my favourites would be electricity and normal, simply becaue they each have only one weakness and only one thing they can't hurt. Also, electricity tends to get paralysis related abilities, and decent speed,both of which fit with my "Neutral, fast and not necessarily strong" preference for non-pokemon-style battling. But in pokemon, it would have to be ... I* don't really have one to be honest. I mean, they each have a whole bunch of appealing qualities; Dark has Umbreon (and doesn't have a 'common-type' weakness); Fire has Arcanine (it's a dog that breathes fire); Water is versatile and normally comes with a nice combo-type (like poison, ice, flying, psychic, etc); and Grass tends to have some good versatility by itself (and is a common mix with poison), so you get everything from tanks to fighters to speedy-things *cough*sceptile*cough*, and it can also get leech seed, poison powder, stun spore, mega drain, etc so it can be used as stalling-mess-your-shit-up-er.
