Depends what you are looking for.

-Kyou Kara Maou! is all around good. A nice balance of humour and drama.
-Fushigi Yuugi put me through an emotional roller coaster sometimes it felt as if the stuff was too soap opera-ish. Nonetheless a good fantasy series.
-xxxHOLiC it is nice with humour, seriousness and a bit of philosophy.
-Sailor Moon, more specifically the last season, Sailor Stars
-Tsubasa Chronicle
-Elfen Lied, if you like goriness go for it.
-The Vision of Escaflowne