I'd want to try being an ISTJ! I've known two friends that are this type... and we think so differently, it's sort of amazing. And I admire them a lot. I wonder what it's like to view the world through their brain!
"You may be one person to the world, but to one person you may be the world."
Haha, that's a bit of a cop-out, I know, but even though I'm not UNhealthy, I could probably stand much improvement.
Being an INFJ or ENFJ might be nice. I feel like I'd get along better with women and be more feminine. Maybe. It would just be nice to not be so wigged out by emotions (I love me some Fe, I just don't know how to wield it).