Reincarnation’s sort of a pleasant notion if not for the fact that average Joe (me, this guy) can’t remember what he used to be. I’m not up on the particulars of the phenomena but I’m pretty sure that’s how it works. I also wonder where are all those billions of new souls are coming from (perhaps a molecule can contain a soul?), but I won’t subject you to my thought processes.
This has probably been overused but I’d want to be an avian of some sort, perhaps a Haast’s Eagle (Harpagornis moorei) because I’ve always wanted to live in New Zealand and being the last of a species seems like an important thing. If some other soul out there decides to also be a Haast’s Eagle and preferably chooses to be reborn as the opposite sex from my own then we’ll really have something.