You have a very good point on the
JS-III. The "Pike" shocked everyone at ther Berlin parade in 1945, but it was everything the Russians could do to keep any running at all. They only sold a couple hundred to Egypt and Syria and most wound up being captured intact but broken down. In spite of the inovative design (I am 100% convinced that we copied that for the M-48), and huge 122 mm gun, it was a mechanical nightmare and it could not be kept operational. It's successor (?) was the T-10, and was supposed to replace the ailing
JS-III and was equipped with improvements to the gune, fire control and NBC protection....However the designers performed a major vertical intercourse and made the road wheels way too small for the tanks weight and the wheel bearings wouldn't last for more than a few miles before they crumbled. It was taken out of production within a few months.
Candidate for worst;, Russian T-10