I am just going to repeat a bit of advice I received on some forum years ago, which I found, to my dismay, to be completely accurate: The best camera to use for your selection of M42 lenses is a Contax 139Q with an adapter.
I have owned, over time, almost all the M42 Pentax bodies, 4 different Fujicas, MamiyaSekors, Yashica TL Electro X, a Praktica, everything mentioned here and a few others, everything except the Chinon.
I have a wide variety of M42 lenses from a wide variety of manufacturers. After moving to Contax 139s with cheap adapters, I’d never go back to any of the original M42 bodies, as they are all clunky to use in comparison. The Contax has a notably clearer viewfinder than any of them (which matters because even though you will be doing a version of stop down metering, the vf is so bright you can compose and meter and shoot with the lens stopped all the way down to f/8 and still see what you are doing), more accurate modern shutter, uses commonly available batteries, has a meter and a good one, is small and light, relatively cheap, easier to find in working-won’t-need-CLA condition, 1/1000 shutter speed, and on and on. I have owned a 139Q since the late 70’s and it has never needed anything in the way of repair or adjustment.
For someone just trying to figure out if they like using film, the last thing you want, to make that determination fairly, is a camera that gets in your way, you’d want a camera that just makes life easier for a beginner, and, frankly, easier and more predictable for an experienced photographer. I like museum pieces, and use cameras going all the way back to the Thirties, but the Spotmatics are going to feel like museum pieces in comparison, in use, and Spotmatics are probably the best of the breed.
Plus, if you find that you really enjoy film photography, you can eventually stick Contax Zeiss lenses on it as well.
Just a suggestion for a different approach to a common dilemma. Please don’t hate me.