Context: I mostly shoot portraits, some weddings, and landscapes. A used EOS 3 was my first piece of Canon SLR equipment.
This film SLR used to be wickedly good, it just had one minor glitch, but then with age it somehow got a major glitch and is no longer so wicked. The minor glitch was that the 2 second timer was for some reason programmed in as a 2 second shutter speed. Random, but not a big issue. The major glitch was that, after not being used for a white, in 2017, the autofocus was suddenly back-focussing regardless of distance, aperture, or lens used. That was a shame because the autofocus was my favourite thing about this camera.
Speaking of autofocus, this thing had a 61-point autofocus system and Eye-Focus control, which actually worked! You look at an object through the viewfinder and the lens would focus on that object. It was excellent, why is this still not on digital cameras? (That being said, the touch-focus on new cameras may make this irrelevant now...)