The R4S is a wonderful camera (one of the best SLR ever built IMHO), but unfortunately the electronics is rather unreliable and there are no spare parts to repair it.
I'd say go with the F3 and the AI-S lenses, which are fantastic. I'd actually go with an FM2, but that's just me. Just don't expect a soft shutter as on a Leica M or even R, but more of a loud metallic CLONK that will people turn their heads in your direction. 😀
If I'd go back to film SLRs, I'd actually get an Olympus OM-1, an all-mechanical, lightweight and small SLR -- one of the most iconic SLRs ever built.
Edit: just realized that the OP already made up his mind