Fruits Basket was THE Shoujo manga that definied all other Shoujo mangas for me. I especially liked the insight you got into the characters, that the anime didn't quite pull off. The characters were rich in spirit, and you don't see a lot of that in manga today. Like, how Tohru Honda seemed too good to be true, but beneath that she was struggling with her own depression, and feelings of inadequacy. All of the characters had trauma, all of them were hurting, and all of them were trying to find & define themselves. There was a level of pain, and depth to it that many Shoujo manga don't even TRY to touch on. For a "fantasy" manga, it felt a lot realer, and hit home a lot harder than any Shoujo manga ever has for me.
If you haven't read it, you should. Even if it doesn't seem like your thing, or it isn't your prefered genre, it's the type of manga where there is definitely something in it for everyone. An absolute must-read.