Voice-wise I'd say Erlock Holmes from Eikoku Tantei Mysteria since he was voiced by my fav seiyuu Chihiro Suzuki. But personality-wise... I'd say Kazuki from Starry*Sky ./////.
a very hard question indeed I guess my most favorite of all time is Masaki Shinnosuke (and I love his seiyuu so +1000 but yea), I love everything about this guy especially his hetare side XD
but my current favorite right now is Madoka from CZ
It's hard to pick just one, but a recent favourite would be Hattori Hanzou from Nightshade - brutally honest, yet caring & supportive at the same time.