Best is a hard young to define. Strength, character, usefulness, these could all be used to determine that in different ways. I'm going to take it as who is my favorite and that would be Soul Long Brooke. While not as powerful as Zoro with the sword, his speed, endurance, tenacity, humor and so much more make him an awesome character to me. Changeling the cold of hell, being able to effect souls, change moods and he killed a dragon. Hell he fought big mom solo and survived. Gotta love Brooke.