Gonna have to go a little bit against the grain...you just said "Sailors" so I'm gonna take that and run with it.
Edit: I just saw that you meant the main 10 Sailors (didn't see that before...oops) but I can't possibly ignore the others. Sorry
1. Cosmos/Chibi Chibi Moon
13. Moon/Chibi Moon
14. The Sailor Starlights (I do like them, but I kinda like everyone else more)
15. The Sailor Quartet (eh, their hair bothers me)
Unlisted: Sailors Chi/Phi, Sailor Luna, the few musical-only Sailor Senshi, the Sailor Anima-mates, and anyone I may have missed.
You know, I find it really hard to just "list" them in order from my most to least favorite...I honestly love them all and my favorites change on a daily basis. Overall, my absolute favorite is probably Cosmos because I feel like her story was the most emotionally satisfying for me. I generally like the Outers more than the Inners, but today Saturn comes first, and Sailors Galaxia and Kakyuu are both just so awesome so I had to throw them in there. Moon and Chibi Moon are so similar so I counted them as one.
I wish we could've seen more of the Quartet but their hairstyles are just so ridiculous, and I know very little about them. The Starlights are okay and I don't dislike them, but they had bad representation in the anime and I just like everyone else more.
Honestly, when it comes to the Inners and Outers, I like them all equally, with my "favorite" in both groups rotating depending on which episode I'm watching, etc. I do tend to like Jupiter and Venus more than Mercury and Mars, but the latter two have their strong points that I adore, as well. I also tend to prefer Uranus and Neptune over Pluto because I know more about them, but Pluto is also quite awesome and mysterious.
This is really hard l o l. I claim the right to change my list at any given time, haha.