I have never seen openings that better fit the show they belong to. Hands down my favorite anime openings. Just watch them if you haven't seen them. If you have, you know you want to watch them again.
Guren no Yumiya and Jiyuu no Tsubasa - Linked Horizon
Guren no Yumiya
Jiyuu no Tusbasa
this video has both themes back-to-back