In regards to the Ami thing - I agree that they are shallow reasons for disliking any of the senshi. I have to say, out of the inners, Mercury is my least favourite - I can't give a definite reason why, because I dont have one - perhaps I just prefer the other senshi more, rather than like her less? BUT I still like and respect her as a senshi and Usagi's friend and guardian.
I can totally understand that. I have a senshi I like the least as well from the group, but that doesn’t mean I dislike or hate them. Maybe I can’t relate to them or don’t care much for them, but all the girls have well-rounded personalities and their weaknesses or drawbacks have clear reasoning for why they’re that way. So yeah, that’s totally fine, especially if at the end of the day, you still respect all of them. :)