I'd agree with having a post-op transwoman as that's not seen very often, but I'd kind of like to see her not being petite. So often transwoman are portrayed as looking very feminine and the only times they are shown as having masculine features is when it's used as an insult.
I think it would be nice to have a transwoman who still retains some of the masculine bone structure, yet is still shown as a woman. Not every transwoman can 'pass' successfully no matter how hard they try, and some positive representation of that would be nice. You don't have to 'pass' to still be a woman.