The Argus C3 35mm rangefinder is the oldest camera that I own that I still use. I keep one of the following lenses permanently attached to a body so I do not have to spend time switching lenses:
35mm f/4.5 Tele-Sandmar
50mm f/3.5 Coated Cinta
100mm f/4.5 Tele-Sandmar
I do the same thing with my Argus C3s. I felt like I had a stroke of insight when I realized the cameras were so cheap that I could just buy one for every focal length.
On the subject of having and using the Argus C3, my only real problem with the camera is the lack of strap lugs on the body. If you want to carry it with a strap around your neck, it's necessary to attach the bottom half of the case. Someone online called the case a lunch bucket, which gives you an idea of the size of the thing.
In general though, I can't say enough good things about the C3. They're cheap and reliable, supposed to be easy to repair (though I've only cleaned the viewfinders and adjusted the rangefinder on mine). Part of the appeal to me is the fact that they're common; virtually no one treats them as precious, and no one goes to great trouble and expense having them repaired. I'm not ashamed to admit I think Argus C3s are cool though it is the moped of the camera world.
My project these days is finding one in bad enough shape that I can work on it, replace the leather and adjust the sync for electronic flash. Any bodies in bad enough shape on eBay usually go for more the ones in good shape (I've seen this perversity too with folding cameras missing bellows and lens).