Yo Ima let you finish but Gundam Unicorn has the
best OST and
sound directing of all time. I sometime see these shows where there's a half-decent OST but it gets pushed so far back into the background that it might as well not even be there. (e.g. Shield-bro from the recently aired stuff. They play "epic music" but it's not well timed, doesn't align to anything, doesn't match to any characters, might not even notice it if you weren't specifically looking for it. )
On that note, Sawano Hiroyuki isn't getting enough love in this thread. Dude is literally in a class of his own. I see the popular stuff mentioned (like Shingeki no Kyojin, Kill la Kill, Guilty Crown) but some of the real gems are ones like: Koutetsujou no Kabaneri, Aldnoah Zero, Re:Creators, Owari no Seraph. AFAIK, they didn't get quite as much love in the west due to meh plot/writing, but the soundtrack and sound directing are god-tier.
I think Key/Visual Arts/Maeda Jun (Kanon, Air, Clannad, Angel Beats, Little Busters, Charlotte, Rewrite) deserves a mention as a package. They're all pretty good.
Most of the "little girls make music" animes have good music throughout, but I also kinda feel like obviously they should... (K-ON, Love Live, WUG, etc)
One last show that I think deserves an honorable mention: Trinity Seven -
Memorable themes. Good sound directing. EDs are all surprisingly high quality character songs
