Gimme, ranked:
Saiyuki
Fushigi Yuugi
Rurouni Kenshin

These are my Top 3. Ofcourse, I also like, 
unranked:
Slayers
Cardcaptor Sakura
Inuyasha
Vampire Miyu
Juuni Kokki
GTO
Ayashi no Ceres
Aquarian Age: Sign for Evolution
Angel Sanctuary
Chobits
DNAngel
GetBackers (AWESOME!)
Fruits Basket

And I got a whole lot more on Manga and DVD. If 
I count both DVDs and manga, I have like 100 
different series. 
If I could only recommend one series for the 
rest of my life, that'd be Saiyuki though.

^^
Anna