Seems like whatever old camera some have they consider a classic. For me a classic should have some significance with regard to camera history, yet manufactured in numbers sufficient to have been easily available. For example, the M3 spelt doom for other rf cameras, all other Ms are simply modifications. Likewise with the F.
If I didn’t miss it while reading the above lists, my candidate is the Rollei 35. That camera’s small size devastated most of the subminiature camera market with the exception of the tiny Minox.