Many people think that "Charlie Chan on Treasure Island" with Sidney Toler is the best overall Chan movie, and I would recommend watching this film if you have it available. My other favorite Toler films are "Murder Over NY" and "Charlie Chan in Panama".
As for Winters movies, he does a decent job playing Chan, but most people think he ranks well below Oland and Toler. Winters only made 6 Chan movies, in a short time frame, so there wasn't much time for him to develop his skills in playing the part. I think "Docks of New Orleans" is his best performance as Chan.
It is really hard to beat Charlie Chan at Treasure Island. That final scene with Charlie doing the hypnosis job is just totally riveting and the most suspenseful finale in the entire series, just brilliant!!!!