Now you have a long list of suggestions; I agree, much depends of your notion of coolness!
May I suggest: Reflex Korelle (made in Dresden 1935, probably the very first medium format SLR; hard to get but not totally impossible; just wish mine hade a more reliable shutter, needs some CLA)
Then we have the hold bunch of folders (not hard to get), at least some would fit any idéa of "coolness": my favourite is a Zeiss Super Ikonta, 6x,6 with Tessar 3,5/75mm, with coupled rangfinder; not just cool, also really SUPER! As to sharpness, I can't really see any significant difference between this Zeiss Tessar lens and the Zeiss Planar 2,8/80mm to my Hasselbald.
But when it comes to people looking at you, I would recommend a HB 500 EL(X or later)
Good luck with the "cool factor"!