My old Kodak Instamatic 500 is dead quiet, sometimes I'm not sure I've taken the shot but it has a self cocking shutter so I don't make accidental double exposures like I can with my Yashicaflex. Both are leaf shutters so very quiet.
The Elan 7 was supposed to be the quiestest EOS I thought. I have a 1NRS and even without mirror slap I find the shutter to be kind of noisy, metal curtains and all. The 1V's autofocus is second to none, the 1N isn't bad but my old 10S and 650 often fail especially in portrait orientation with the old BASIS sensors.
Often it is simpler not to have to focus at all, my Kodak Instamatic has scale focus and for street that can be the quickest, just prefocus, preset the aperture and shutter speed and just shoot.
Depending on the location I've done street photography with all the cameras above, Canon FTb or even the Mamiya RB67 which is HUGE (sometimes mistaken for an old movie camera due to the bellows focus) and sounds like a door slamming shut with the 6x7 mirror! The separate film advance and shutter cocking sounds a bit like a bolt action too.