I'm pretty sure Aerith is the right way, but I always call her Aeris because of FFVII :P

I don't remember what I called her on The Sims, but when I put videos of them on Youtube I name her Aerith so avoid being corrected XD

I have a friend who's watched Advent Children and is a big Kingdom Hearts fangirl, but she hasn't played FFVII, and when I said I might cosplay as "Aeris" she was like Oh my God, did you say Aeris? Then she laughed at me