Well I’ll just list some from those genres that I think are good:
Music
Sounds of Life (Kono Oto Tomare!)
K-On
Hibike! Euphonium
Nodame Cantabile
Anonymous Noise
Action
Darker than Black
Seraph of the End
Chivalry of a Failed Knight
The Irregular at Magic Highschool
The Saga of Tanya the Evil
Full Metal Alchemist Brotherhood
Romance
Hyouka
Kokoro Connect
Gosick
Kimi ni todoke
Oregairu: My Youth Romantic Comedy Is Wrong, As I Expected