Cameras like the Voigtlander Bessa II and the Zeiss Ikontas are the classics at the high end, but there are lots of neat folders for not too much money out there. Do a search and you should turn up a couple of threads on folders.
Check out an eBay seller named Juergen Kreckel, who goes under the username "certo6." He buys and refurbishes old folders, and sells them at very reasonable prices.
I've looked into those Fuji rangefinders, and they are just too big and bulky for what I want out of a 6x9 camera, though they are certainly good cameras with more modern focusing systems and lenses and most likely better film flatness than a 1950s folder. A folder will fit in an overcoat pocket. A Fuji 6x9 rangefinder is about the size of a brick.