One Piece is the best shounen anime ever made. Hands down. No contest. Bleach, Naruto, Gintama, and all those others have nothing on One Piece.
What you got is an EPIC story.
What you have are AMAZING characters.
What you see is COOL art and animation.
What you experience are AWESOME levels of entertainment.
You can't even say it's a competition about which is the best anime. This is it. One Piece is IT.