For me, without a doubt, the quirkiest and worst was a dumbed-down Exacta called the Exa.
Ah yes, the Exa. This post brings back more long ago memories.
A cousin of mine had one in he 1960s when I was getting serious about photography - he bought it cheaply off a friend who had been with the Royal Canadian Air Force in Germany. I was getting into photography at that time and had just bought a Yashica D TLR, so on Sundays we often went out shooting B&W landscapes together in the eastern Canada countryside.
Nothing about that Exa ever worked right. Most of the time it did not even run the film through its innards, tho' I now believe that was the fault of the photographer and not the equipment. It focused badly and the exposures were consistently off. I processed his films for him and of course he blamed me (at first) for the poor results until I showed him my 120 negatives of the same 'scapes, which were fine.
One day he got so exasperated with it that he threw it against a barn door. It bounced and landed heavily on the ground but his effort did no visible damage. It kept working but the results were as bad as before.
He and that camera just did not get along. I could not be bothered to try it out as I wasn't into 35mm at the time, so I never know if the fault lay with him or with the Exa.
A few years later he found religion and became a lay preacher. The camera went into the cupboard in my grandparents' house. It may yet be there for all I know but as I now live in Australia I will likely never get to find out.
The only other Exa I ever saw in my entire life was one a co-worker in Sydney in 1977 wanted to sell me. He was German and it has come to Australia with him. I passed on it.
I did think it was rather a cute small camera, if dysfunctional - odd for something made in Germany.