I like Watson in the Rathbone movies as well.
Nigel Bruce is who I see in my mind whenever I think of Watson. He also resembles Conan-Doyle a bit. My Daughter gave me a set of old Sherlock Holmes dvd’s. It also included a short video of Conan-Doyle. He actually reminded me a good bit of the character Watson except of course he was not at all bumbling.