Serena (aka Sailor Moon): Although I've come across people who say that Serena is the worst thing about Sailor Moon, I happen to think she is one of the best. While I can understand people favoring the other scouts, I think that it was nice to make the star of the show the 'imperfect' one.
Amy (aka Sailor Mercury): Amy happens to be my least favorite Sailor. She seems to be the most boring of all of the Sailor Scouts. I mean all she ever really does is STUDY! Now that's not very interesting. I did think that befriending such opposites as Serena and Amy was rather interesting though.
Raye (aka Sailor Mars): I like Raye, even though she is in my opinion (duh!) one of the meanest scouts. She is constantely putting Serena down (Although even I agree that she sometimes deserves it!), and her attitude isn't always focused just on Serena. She seems to take an attitude towards everybody sometimes.
Lita (aka Sailor Jupiter): I think that Lita is one of the nicer scouts, since when she first ran into Serena on the way to school she defended her even though she was a stranger. She also seems to care a lot about the other scouts and just other people in general, even though she fights a lot.
Mina (aka Sailor Venus): Mina is one of my favorite scouts. My only gripe about her is that she seems to be a little bit self-absorbed. I have only seen her in the end of the 1st series and the beginning of the second, so I can't really pass much judgement on her yet.
Although I like and dislike sone of the Sailor girls, I understand that they all play an important role in the Sailor Moon series. The show is about friendship and teamwork, and it is crucial to include characters with varying backrounds. Even though I may not like one of the scouts as much as another, but the show wouldn't be the same without all of them.