A couple of my favorite (not exactly OP nor ED), in no particular order:
Vogel im Käfig by Hiroyuki Sawano:
Merry-Go-Round by Joe Hisaishi:
Crime and Punishment by Akira Senju:
Komm, süßer Tod by Shiro Shagisu:
Just recently got into anime (though I have experience with Studio Ghibli)...