Some things I love about One Piece:
The main characters are not brought together for one central mission, to save the world, or to benefit anyone else. Each joins the crew with an absolute mission of their own, to be the best at one thing or another, or to further their own dream, and the 'captain' wouldn't have it any other way.
The way the crew roams the world, freely, and to experience all the awe and wonder of the world around them.
Although some would think the World Government is an enemy or antagonist in the show, it's really more like they are just in the way, just an afterthought