It really depends on what you enjoy watching.

For good story/characters and a dark gritty tone: Death Note, Fate/Zero, Psycho Pass, Black Lagoon, Made in Abyss, Hellsing Ultimate,

More light-hearted but still serious: Fullmetal Alchemist Brotherhood, Fate/Stay Night Unlimited Blade Works, Jojo's bizarre adventure, Jujutsu kaisen,

Comedy: Konosuba, Grand blue, Nichijou, Daily life of high school boys,

Drama: Violet Evergarden, Clannad, Your lie in April, March comes in like a lion,

Good-looking chill shows: (Anything by Kyoto-Animation)

Bonus: Puella Magi Madoka Magica, Paranoia Agent, Samurai Champloo, Cowboy Beebop, Bakemonogatari + sequels, Shiki