A hard question as I like different cameras for different reasons. I've not found one that is not a compromise is some way.
SLR: Never had a Pentax LX but based on my experience with the Exactas I suspect it might be a favorite if I ever put a system together. Also, as many of the features it has as to configuration ability is similar to my Bronica ETRS with the 35mm back that I would class as my favorite 35mm SLR I think the Pentax would be it. However, the Bronica has been so good that I've not in decades had any desire to put together a 35mm SLR system.
Folders: Easier; Minox ML and Voigtlander Contina II (524/24). Each folds up to a very easy pocketable unit with excellent lenses, especially with color film. Of the 2, the Minox sadly has a troble prone electronic shutter and why there are almost none around any longer. I've not tried the GT that seems to have a corrected shutter and was the last of the series so I do not know if I'd like it as much simply b/c it does not have manual metering or meter hold. So, the Contina II is the winner. I've owned mine for some 30 years and only a few years ago did the shutter finally gum up so it is awaiting a trip to the doctor. I expect it to easily run long after I'm dead.
Viewfinder: The Vito B wins hands down here. The Pronto SVS with Color-Skopar lens is a killer combination and whatever the company did to finish the camera's metal parts should be studied by every manufacturer. The parts never seem to show wear, rust, scratch, mar or anything else. Mine has not been abused but not babied in ANY way and it is in like new condition looks wise. The lens name is very appropriate as it really brings out the colors. Saturated and contrasty colors without making it look false.
Rangefinder: Yeah, an easy one, the Leica CL. Small, great standard lenses, pocketable, built as good as most though not a hammer like a M Leica or the Contina or Vito B but weighs mush less than any of them. Built in meter is as good as anything I've used. I've tried an M body from time to time as I'd really like to get one but each time even with the cash burning inmy pocket, it just did not do it for me as well as the feel o the CL. If did not have the CL, maybe then the M body would have worked for me. I had mine serviced back when I bought it in about 1987 and it has been a very reliable constant companion since. No shelf queen or sometime user but my main 35mm camera.
If I had to only select 1, discounting the possibility of the Pentax LX and accepting all the flames ( I can se them coming) that the Bronica does not count it would be difficult to choose between the 3 remaining cameras. Each is so different from the other though the Vito B and CL are basically viewfinder cameras but the CL has more options. All 3 sort lenses that are so good that for general color negative photography they are almost equal. The Vito B and Leica do better than the Contina II with slides while the Contina II and the Leica do better than the Vito I like better with slow ISO b&w, the Contina II is really nice with faster grainier higher ISO than the Vito II.
Based on the above, I think I'd have to go with the CL but if the question were to arise AND I really had to choose I'm not sure. Happily, I do not have to make a choice.
