Man this is tough.
Also, I’m really terrible at remembering & knowing precisely which shape is which. Just being honest. Especially when we’re talking about differences between say a Canadian, Liverpool, Bing, etc. Same with Bulldog and Author.
But I suppose, if I could only smoke one shape/type for the rest of my life, I’d have to go with a Churchwarden. Curiously, while these are my absolute favorites, I actually smoke my Churchwardens much less frequently than my other pipes.