My first camera, the Maxxum 7000 had a pair of up/down buttons to toggle through the shutter speeds, shooting modes, etc. Purchased new, hated it after the first week, sold it after six months of misery.
Olympus IS-1 had a very slow power zoom. Very slow. I mean SLOW. Purchased new, lived with it for less than three months, sold it back to the shop for an EOS Elan.
EOS 1, original model. Gorgeous as hell, but I never got on with it. I couldn't say why, either. I have a 1N and 1V that I love.
Contax 167MT has a slider to toggle up/down the shutter speeds. Took four AAA batteries, fer crying out loud. The add-on battery chamber that takes AA batteries didn't fit squarely. Shot two rolls with it, sold it back to the shop when I got an RX. I really hated that slider.
Minolta Freedom Zoom 140EX. Rather annoying user interface. Set it for a macro shot, take the shot, camera resets itself. Deeply disappointing image quality, but that could be my sample only.
I know I'm going to get flamed for this one... Canon EF and Minolta XE-7. I've tried to like them, but loading film in them both is more difficult than it needed to be. Also the XE-7's power switch is right under my right thumb as I'm taking a shot; I'm frequently turning it off when I need it to be on. The EF eats batteries so badly they had to put a sticker by the power switch to remind you to turn it off. Duh.
Sorry if this is on topic...