[A camera where it is easy to] locate the faults, easy to source the parts , easy to repair
You realize you are asking for something that does not, and possibly can not, exist.
Better to ask what is the least evil camera to keep going.
I would say anything without plastic or electronics in the essentials and where donor bodies are available. Though with advances in 3-D printing that may change.
Cameras that could be kept going for a long time: Leica M2, M3 & M4, Nikon F & F2, Rollei's, 'Blads ... and a slew of lower end folders and the like. A $14.95 from Montgomery Wards
Agfa Solina could be kept going to the ends of time (remove green goo before attempting).
It may be possible to remake Photomic finders if one is willing. And possibly cameras with simple electronics: F3, M5, and the like. A few encoders, an Arduino, a couple of LEDs and a photodiode or two and you are in business. Throw any galvinometers in the trash along with the selenium and CdS cells, ring resistors and other unobtainiums.
You would, though, have to be very, very willing. A labor of love with negative business potential.
Anything with a motor drive or lots of electronic gee-gaws would be hopeless to keep runnning for the next century while a 100 year old Kodak keeps chuging along.
Getting film will become harder and harder - just like finding contemporary 112 for that old Kodak. 35mm will be impossible to make without a perforator.
Maybe wet-plate and tin-type are the way to go. Film is always available and the cameras meets the criteria of easy to locate the fault (it should be staring you in the face); easy to source the parts (lumber yard and hardware store); and easy to repair (saw, hammer, nails, pot of glue).