I would like to do a write in vote for Xinyuan Xu. I have little to go on to base my vote, but he at least did have a sequel made, so that should count for something.
Manuel Arbo but I'm not sure how well any of us could really decide on who because we've either never seen the performance or it might have been years . . . .
And Manuel Arbo does come closest to the Charlie Chan we know and love.
J.Carrol Nash gets my vote. Manuel Arbo is very good, but the language barrier detracts a point or two for me. I am often too busy reading the subtitles to watch the actors. I manage, but it is a bit distracting. And then there is the fact of the only one movie. J. Carrol Nash was a fine actor and if he had a full hour show, instead of the half hour with so little time to develop characters and storylines, I think we would be remembering him above Roland Winters. As it is I think he is the "best of all the rest". Call me crazy, but I see a bit of the old Chan charm in him. He has over 3 dozen TV episodes to his credit and even has on screen time with a # 1 son. The silent and other early Chan actors amount to little more then cameos. Ross Martin, if I recall him correctly, was "stereotypicaus ridiculos". I am not sure peter Ustinov's spoof film portrayal should count. I think I'd sooner count Harry Who