Olympus OM-1: Shutter speed control in the wrong place, flimsy film advance mechanics, gimmicky screen that is too big to be useful. And the worst part is the owners -- they're part of a horrible Koolaid-drinking club that thinks this is the ultimate camera system.
Olympus Pen F (pictured):
View attachment 324605
A candidate for the worst SLR camera ever. Horrible mechanics, horrible shutter (reflective!), horrible porroprism finder optics. I pity the technicians that have to work on them. Ugly big "F" letter on their front fascia probably means "F--k you", a message from Mr. Yosihisa Maitaini to mankind.
Olympus OM lenses: Made with "compactness" as priority #1 above all, which means compromised on everything else.
Olympus 35SP: Meter can't be turned off, not even placing a cap on the lens. Loooong shutter button travel and the loudest leaf shutter ever put on a compact camera.
Do you see a pattern here? But some of my favorite cameras are Olympus: Trip 35, Pen S, Pen W.
Nikon F3. Lol. It could have been a great machine. I could write a book on all that's wrong on that camera. I've already written enough here.
Nikon FM2/FE2: The fact that they don't take pre-AI lenses, while their predecessors could, is an insult from Nikon towards its fanbase.
Nikon FM: The FE is a superior camera in every respect.
Nikon EM: It's ergonomically superb, however very poorly made.
Canon EF. Horrible ergonomics due to the stupid ON-OFF switch, and if you don't turn the camera off, the batteries will drain.
Canon T50: Ugly crap.
Prakticas with the vertical shutter: Shutter has very strong vibrations.
Rollei 35: Great optics and cute looking, but a camera for masochists. Controls completely awkward and whichever distance you set into focus will promptly be resetted as soon as you put it into your pocket.
Leica M system: If I had the money for such a system i'd be buying a Mamiya 7 instead.
Contax RTS: Glorified Yashica. I'd buy a Yashica FR instead. Which is a nice camera (!)
Mamiya TLR system: Most of the interesting lenses are very slow and/or throw the camera off-balance.
Mamiya M645: Bronica does it better.
Hasseblad 500C series: Bronica does it better.