It depends on what you mean by "the best"
Just like tv shows and movies , there are also different genres in animes
want Action & Adventure ? watch : Dragon Ball Z , Black Clover , Naruto , One Piece
want Crime / Thrillers / Mindgames ? watch : Death Note , Dr.Stone , Psycho Pass
want Gore ? watch : Attack On Titan , Demon Slayer , Jujutsu Kaisen , Chainsaw Man , Hell's Paradise
Want mecha ? watch : 86 , World Trigger , Gundam