Last week I found a pipe I had loaded and not smoked. Could not for the life of me remember what it was as it had already been several days since I packed it.Since you mentioned Briar Fox I’ll take that as a “clue”. I’ve never smoked Three Sails.
I also enjoy blends where the flavor comes “primarily” from the tobacco. I’ll call this “plain” but there’s no lack of flavor in “plain blends”
The following short list are pure or plain tobacco or naturally flavored:
C&D Winchester - only two ingredients, Red Virginia and Unsweetened Black Cavendish but just an incredible combination!
C&D Crooner - only two ingredients, Quality Burley and an herb called deer tongue. Another incredible but “plain” combination!
C&D Pegasus - Enough praise has been offered.
C&D Old Joe Krantz Series
C&D Burley Flake Series
HH Acadian Perique - if you can score some. A symphony of pure tobacco’s. Very flavorful and all of that flavor is tobacco.
All of that said, I suggest you try each of the old tyme, over the counter blends because I’m certain that one of these will be an eye opener. And although each of these has a process for added flavorings, they may meet your definition of “plain”.
Granger - of course
Carter Hall
Prince Albert
Sir Walter Raleigh
Amphora
Half n Half
Etc Etc
I smoked it, it tasted great, and I kept trying to remember what it was. After I finished it off I remembered it was Granger.