My personal favorite of all time and widely recognized as one of the greatest of all time.
There is two series one that follows the manga and the other that the author singed off on before the series was over and since she worked closely with it,it contains no filler but,it does have a drastically different ending and themes that diverge from the source material halfway through.
The first series is the one that is hailed as one of the best.
I am not familiar where the anime that follows the manga stands regarding overall best series of all time but,the word is that people who follow the manga like it a lot more.
Watch both lol