Manliest shape? I've no idea but bulldogs and billiards could work for me. Now to skew the question a tad, the manliest pipe...just about any Custombilt.
When I first glanced at that double-barreled Fat Bastard display in dave g's post, I thought they were some crazy binoculars or ergonomic opera glasses before I remembered that this was a pipe thread.
Then I looked at the picture for a moment or two, and from a perspective, the manliness of the form of these pipes became more evident. Like finally getting a joke after everyone else has already laughed.
(Notes to Self: Address original topic and avoid double-posting.)
For manliest pipe, my vote is split between the straight pot (not otherwise specified) and the Peterson Premier System Rusticated 307 (with wear and tear from age and heavy use).
Any pipe I stick in my mouth is pretty damn manly!
But if push came to shove, I'd have to say Vulcano.... it's just hard for me to picture a woman smoking one.
I've waited to comment because I really wanted to see what a bunch of guys, all of whom stick something in their mouths to suck on, would say.
Manliest shape my arse!