I choose the K1000.
It has been my go-to SLR for more years than I care to count any longer. It has been the perfect camera for me.
I'm not sure that most people really understand this, especially when we have become so accustomed to buying a new digital camera every two years, but I have used this camera for so long that it is like an extension of me. Within seconds of picking it up I can recall again in my mind exactly how many clicks (and in which direction) it takes to get from 1/2 a second to 1/60 seconds on the shutter dial. I really don't need a readout in the viewfinder to know the shutter speed. I can close my eyes and slide my fingers along the gap between the ridges on the aperture ring of that old 50mm f2 lens and tell almost exactly where the aperture is set. A window in the prism housing to show the number is superfluous. The little balancing needle is the only thing in that viewfinder, and it works perfectly for me. One glance at that needle and I can tell if I am a stop or two above or below what the meter believes to be the perfect exposure. After 28 years of pretty much steady use the plastic cover on the film advance lever was worn out, but Eric kindly replaced it with a new one when I finally sent it in for service last year.
Most people have long ago decided they need something more sophisticated and the K1000 just doesn't fit their picture of the world any longer. It is just a student's camera after all. But it is the perfect camera for the minimalist.
I choose the K1000.