Inu X Boku SS was one for me. I didn't quite care for Ririchiyo and Mike, but I really liked Sorinozuka, Nobara, and Kagerou ("Everything is either an S or M!"). I also wish the anime would follow the manga and get another season.
Naruto and Bleach were ones as well. I like the other characters more than I like Naruto, Sasuke, and Ichigo.