Can't Pick only one. Gotta go with these.

I hate picking favorites.  That said, OPs for me are all about the music, and these are some of the more memorable
 ones (in a good way)...

and of course the KoS japanese version...

sends chills down my spine everytime

Nobody can chose just one @Persona

I always rather liked this one.
 

I really enjoyed seeing all of these openings! Some I've seen for the first time. I did jam out to a few of them. A couple threw me way back and that was a good feeling! But the one I enjoyed the most was the Gakuen one by @bluuenvy .

Thanks for playing everyone!

Envy, 

Please let me know what kind of doodle you'd like for me to draw! I will make it a decent size to use in your signature or as an avatar picture.