My top fave is def. Ivypool - I love her dearly! Mapleshade is my favorite antagonist, and I love how she pretty much set up the events of the main books - and hey, even ol' Tiggerstraw was afraid of her!
Hawk Swoop is my baby, too, and Petal, Turtle Tail, Falling Feather, Quick Water, Sparrow Fur, and Fern have all become very impressionable characters, too.
I don't like too many Warriors toms - at least, not nearly as many toms to she-cats, but I do like Whitestorm and River Ripple!!