Lucky Star and K-on for CGDCT
Evangelion for meta-commentary and deconstruction, to the point that future works that qualify often get called the “Evangelion of <genre>”
Fullmetal Alchemist Brotherhood and Attack on Titan for battle shounen
Bocchi the Rock for girls band anime, specifically
Lupin III: The Castle of Cagliostro for pretty much all of Ghibli
Akira for 90s anime
.hack//SIGN did not age well. It got some decently positive reviews when it first aired, but was just about unwatchable when I rewatched it ten years later. But yeah, the soundtrack (early Yuki Kajiura) was always the best part.