This is an easy question for me to answer. I am undoubtedly most like Ami/Mercury. These are just some of the examples why :
* We are both very intelligent and did very well in school.
* We both have a love of learning.
* We both wanted to get into the same career path as our mother (although we're different in which career path that is - hers is being a doctor, whereas mine is in the computer field).
* We both studied a lot in school, often to the point of neglecting to try to get more friends.
* We didn't have very many friends.
* We are both shy to the point of not wanting to start conversations ourselves.
* We both focus a lot on being polite.
* We both have one sport we focus on and excel at (although one difference is in which sport - she is into swimming, whereas I am an avid bicyclist).
* Both of our favorite colors are blue.
* Both of us have parents that divorced when we were young kids.
In fact, about the only major way that I am not like her is that I am not modest/humble.
I am also a lot like Hotaru was in S season. I have been diagnosed with depression, which it seems like Hotaru had that year (true - she didn't show it when she was with Chibi-Usa, but she did show it at pretty much all other times). Plus, neither of us are very good at face-to-face social interaction.