My top 5:
Visions of Escaflowne
I've also watched a few episodes of Lucky Star but I didn't like the later episodes as much.
The other old school stuff like Digimon, Sailor Moon, Attack No. 1 etc. were also enjoyable but didn't stick with me as much as the other ones I've listed in my Top 5. I've lost interest in Anime heavily though, I only keep up with Naruto and that's about to end soon as well.