I'm gonna hafta say my absolute favorite is Fruits Basket. The storyline is soooo cute, it's absolutely friggen hilarious (except for the last few episodes....I cried.... and wanted to kill Akito....)
The romance plot is also very good as well, but it's a rather origional storyline... Usually, when people try to do ppl switching species storylines (like, for example, ranma 1/2 and Fruits basket) they sometimes come out a bit....weird... and take-off-ish, because Ranma 1/2 is so popular, But Fruits Basket turned out absolutely EXCELLENT! I like Ranma 1/2 too.... it's so.... um.... I don't think there's actually a word to describe it... sweatdrop
Least favorite? GHOST IN THE SHELL!!!!!! ugh. The animation gives me nightmares, the plot doesn't hold my interest for S@#$ and did I mention that I HATE THE ANIMATION WITH A PASSION!!!!! I don't know why... but anime that is too realistic really, >really< bothers me... stressed