Angel Beats OP , ED & OST
Spice and Wolf & II OP
ef - a tale of memories OP
AIR OP
Romeo X Juliet OP
Bakemonogatari ED
To Aru Index & Railgun all OPs, Railgun EDs
Gosick both EDs
So ra no wo to OP
Asura Cryin OP 1
Seikon no Qwaser OP 1
Code Geass R2 OP 1 & 3
REC OP
Well~ I can't think of any more now (and I also can't settle on one favorite from those)
Spice and Wolf & II OP
ef - a tale of memories OP
AIR OP
Romeo X Juliet OP
Bakemonogatari ED
To Aru Index & Railgun all OPs, Railgun EDs
Gosick both EDs
So ra no wo to OP
Asura Cryin OP 1
Seikon no Qwaser OP 1
Code Geass R2 OP 1 & 3
REC OP
Well~ I can't think of any more now (and I also can't settle on one favorite from those)