I have quite a few favourites: (And by a few I have a lot)
https://www.youtube.com/watch?v=HDd658GYvng
https://www.youtube.com/watch?v=kpajJi5yBsM
https://www.youtube.com/watch?v=Aw3fN3OPk3A
https://www.youtube.com/watch?v=C_t47BVtPuE
(Come to think of it I like most of the FMA:B openings)
https://www.youtube.com/watch?v=XMXgHfHxKVM
For favourites I'd have to say Full Metal Alchemist: Brotherhood, Gurren Lagann, Magi (Labyrinth and Kingdom), Darker Than Black, Log Horizon and Toradora