C'mon, TANK! is in my top 3 since it's actually good and Cowboy Bebop is one of my favorite anime. We Are! ENG dub because it kinda gets me teary-eyed since I've been watching One Piece for years now and it's my first anime. Lastly, the Evangelion op because it's so grand.
God, what the hell is this post. Add all GTO ops and endings on here. And Naruto's Viva Rock.
I really like the 8th and 9th OPs for Boruto (helped by the fact that the current arc is from the manga and is at a much higher quality than previous arcs so I guess Studio Pierrot pulled out the good animators for these ones)
Also the 17th ED (also from the current arc)
I think the other OPs/EDs are good at best to bearable at worst.
While the song itself may not close out a single episode, the song does close out the entirety of the 13 episode anime. Almost immediately after, the credits and then post credits scene rolls so I'm counting it.