Interesting question. I have, I dunno, maybe 120 or so, but many of them do not work correctly, and quite a few are odd formats that no film is commercially available for (and I'm not willing to have custom film rolled for). Slowly I'm rectifying the non-working ones, but there are some that will never be used, sadly. I'm going to probably be divesting myself of many of my curtain-shutter 35mm SLRs fairly soon, which will free up a lot of space on my piano for new old junk
I cycle through the working ones, though my current carry-round cameras are a couple of 35mm rangefinders I've repaired to working order: an Olympus 35-S and a Ricoh 500, the one that has the bottom-wind trigger, and a 1938 120 Voigtlander Bessa.
Edited to list makers:
Graflex, Norita, Canon, Alpa, Olympus, Fed, Zorki, Zenit, Pentax, Voigtlander, Rolleiflex, Mamiya, Busch, Yashica, Cosina, Minolta, Argus, Sears Tower, Kodak, Zeiss Ikon, Bolsey, Dehel, Hanimex, Diana, Nimslo, Nikon, Stereo Realist, Edixa, Iloca. There are probably more but I'd have to go downstairs and look.