Getting into a sequence with more than 1,000 episodes is complicated, but 1 Piece is worth it. It isn't really considered the greatest anime of all time for almost nothing. One Piece provides several of the most intricate, subtle world-creating and ideal storytelling in anime.
2021 update: I've been on the fence about deleting this as it's so inadequately created, I was seventeen at enough time of creating and not a local speaker, and my impression on a single piece here and anime in general has improved considerably to the worse.