Cowboy Bebop- All rounder
One Piece: Hikari e
Kokoro no chizu
BRAND NEW WORLD
D. Gray man:Yume no Tsuduki he
BLEACH: Happy people
Full metal Alchemist: Tobira no Mukou e
Busou Renkin:Makka na Chikai
Gintama: Fuusen Gam
Outlaw star:Through the night
Top 5 manga: 1.One Piece, 2.Reborn, 3.D. Gray-man, 4.Fairy Tail, 5.BLEACH
Some of my favorites are
Cowboy Bebop - Smooth rhythmic Jazz and Blues, fit the series perfectly.
Samurai Champloo - Grade A+ funky Hip-Hop by one of the best producers out there now. Also fit the series wonderfully.
Denno Coil - The music for this series is very original. I can't really explain it well, it's just different. Can't wait for an OST to drop.
I consider BECK: Mongolian Chop Squad's OST as one of the best ones I've ever listened to