what features and characteristics should a "fighting revolver" have if you were in the market for new one, and you knew you would (possibly) be in a gun fight aka might have to defend your life with one?
1. Folks are quibbling about what sort of "fight" would a fighting revolver be used for: CC, SD, HD, war, etc.
2. I would stipulate that they be double action (not necessarily DAO, though).
3. I am focusing on S&W, but there are Rugers, Colts and even Tauruses (Tauri?) that could be interchanged.
Concealed Carry, Self Defense, Home Defense
A concealed carry fighting revolver has to be packable and concealable. I can conceal anything from J-frame up through N-frame, given reasonable sartorial choices and carry gear. I would require .38spl chambering at minimum and likely top off with .44mag, .45ACP, or .45Colt. .357mag is likely a good compromise round. "Nice to have" would be a Crimson Trace laser grip, which I make sure I have on my J-frames for low-light shooting. Were money no object, I would have one on every gun I might tote. Barrels for J-frames would be ~2" and K-L-N 2-4". My actual choices for this category are SW638, SW64 2", SW64 4", SW686 4", SW629 4".
A self defense fighting revolver would not have to be concealed, so that opens up the bigger/heavier end a bit and likely skew my choice. If in wild areas, I would be likely to choose .44mag N-frame for 4-legged threats, though my W64 4", SW686 4", SW629 4" woiuld all serve.
War, Contemporary
I would forego J-frames and stick with K-L-N frames, preferably with moon clip capability. Some gunsmiths can machine cylinders such that even revolver cartridges can be fed with moon clips, though N-frame .45ACP is the no-brainer choice. Again, CT laser grips and maybe a WML. I might want to spring for one of the fancy-schmancy SW tactical type revolvers with a pic rail & moon-clip capability from the factory.
War, Future Post-Collapse
Kinda depends how "collapsey" things are. Maybe to the point where home-made black powder makes a resurgence? In that case, the old spacious revolver cartridges will rule the roost. All my SW revolvers would suffice, but big bore goes naturally with black powder.