Yes i also enjoyed avatar but...Avatar is not an Anime.
The term Anime refers to Japanese Animation. So Avatar is a anime-influenced animation
http://en.wikipedia.org/wiki/Anime
http://en.wikipedia.org/wiki/Anime-influenced_animation
I have ALOT of titles i can recommend. So i just list whatever comes in my mind.
Ouran High School Host Club
Fairy Tail
Ai Yori Aoshi
Shakugan no Shana
Shuffle!
Fate/stay night
Rurouni Kenshin
Vandread
Trigun
Air Gear
Shijou Saikyou no Deshi Kenichi
Honey and Clover
Zero no...