|Huh... the idea of body swap is already unrealistic... Personality changes due to new body/hormones? The closest thing is Boku to Kanojo no XXX. To be exact, it's not really personality changes, but the new bodies fits their personality better than the old bodies. Like, feminine boy becomes feminine girl.
Another one might be Jinzou Shoujo... Other than that, usually the personality stays the same.
Quote from Accursed-kun
The most realistic body swap i ever found... strangely enough... was actually a hentai...
I can post the link if you want >.>