Actually, as a Flask fan and long-time Djangonaut, I'd like to know what you find so good about Pyramid—where does it shine?

No, I don't. I and most people still don't understand what Pylon/Pyramid is and their page that tries to explain it does nothing but make the problem worse.

They belong to the same family of interchangeable parts, seemingly used by people who haven't used a web framework that doesn't begin with the letters Dj.