The various Fed 5's with lever advance, hot shoe and removable backs are common, but I prefer the meterless 5 B with its lever rewind. The Leningrad is also quite interesting, with its built in 3 fps motor. No Soviet Leica Screw Mount RF had TTL metering, though some did have Selenium meters. My advice is to choose the features you like, but don't bother with frustrating yourself trying to find an accurate built in Selenium meter. Most decades old Selenium meters are seldom working today, much less accurate.
Earlier lenses are chrome, later lenses are black.
If possible test mount and focus Soviet lenses before buying them. If your Soviet camera Leica screw mount body breaks, it's probably cheaper just to buy another than to have it repaired. This table is an effort to give a quick overall view, so minor variations and rare limited production cameras have been left out. Disagreements exist about model designations, production dates, and RF baseline lengths. Personally I advise against building a Soviet camera collection, since it's unlikely to greatly appreciate in value during your lifetime.