One of my most favorite shows had to be Redwall. It was so serious and real, the whole thing was like one big adventure!
As for other favorites: Hey Arnold!, The Adventures of Sonic the Hedgehog, Transformers (G1), Batman the animated series, Spiderman the animated series, X men: Evolution, Oscar's Oasis, Reboot, Gargoyles, TMNT (2003), Eon Kid (Iron Kid), and to a very slight degree, Invader Zim and Megaman the animated series.
And for anime, Megaman NT Warrior: Axess (the whole Dark Protoman thing was totally awesome
).