IRL I would want to be Lin. Who wouldn't want to be a metal-bending badass?
Or the Lieutenant. Whenever he gets the crap beaten out of him, he still somehow manages to pop right back up. The durability of that man is amazing.
I'd want to be the Avatar. If I was Korra I'd have been one hell of a d**k of an Avatar. There would have been a hell of a lot more chasms opening and people falling into them. Of course those pits would also have earth spikes for them to get impaled on.