He was not a Ginko boss. He was just a customer that liked to buy rare shit, like human horns or petrified mushi.
So why did you liked him? He was just some doctor in small fishing village. He didnt play big role in any episodes.
My favourite character, I would say, is the women (forgot her name) who saw the future. She had realy strong character and a tragic fate.
Honestly, though, it is impossible to choose the best characters. All of them are drawn very scetchy and yet very impressively.