I really like the Life element. They are by far the most diverse characters in the game, although Earth is probably the most powerful. Dino-Rang in my opinion is the only fun Earth character to play as on PVE, while Stealth Elf, Zook and Camo are all fun to use(for Stealth Elf, just disappear and slash your enemies in the back. It never gets old for me!)
For chumps, I'm leaning towards Air and Tech. Air really doesn't have any stand out characters, although Medea Griffon Sonic Boom and Tempest Dragon Whirlwind are by no means bad. The fact that Warnado was such a let-down when he should have been amazing makes me biased, but I don't particularly like Lightning Rod either. Trigger Happy and Boomer are fun on PVE, but are relatively bad on PVP. Drill Sergeant isn't that great on the Wii either. Drobot is their only decent character frankly.