It depends on what I knew about the gunfight beforehand. If I knew that I would be facing several small-to-medium sized individuals, I'd prefer my CZ-75 9mm loaded with 18 rounds (17 in the mag and 1 in the chamber) of Winchester Ranger T 127gr +P+ and at leas one spare mag full of the same. If, however, I knew that I'd be facing a few large-to-very large individuals, particularly at short range, I'd want my S&W 629 .44 Magnum loaded with Remington 240gr SJHP and at least one speed loader full of the same. If all I knew was that I would be in an unavoidable gunfight and I'd be limited to a handgun, I'd choose my S&W Model 28 .357 Magnum loaded with Remington 158gr SJHP and at least one speed loader full of the same because I can shoot that combination of gun and ammunition better than any other I've ever tried.
Of course, if I were not limited to handguns (and if I had prior knowledge of an impending gunfight I'd do my best not to be), I'd want either my 922r-converted Saiga .223 loaded with 30 rounds of 55gr FMJ and at least one spare mag full of the same or my Remington 870 Express 12ga loaded with 3" #1 Buckshot and the butt cuff full of Brenneke Black Magic Magnum rifled slugs depending on the circumstances.
Of course, like others here, if I knew there was an impending gunfight, I'd be doing everything in my power to be as far away from said gunfight as humanly possible.
So to clarify, is there a reason a revolver would be a better choice? I don't see it but then I'm not a revolver guy.
While the best type of gun depends upon the situation, revolvers do have some distinct advantages that make them better suited to certain circumstances.
-Revolvers require nothing more than another pull of the trigger to deal with a misfire as doing so rotates a fresh cartridge into play.
-Revolvers are also immune to grip-induced malfunctions so long as the shooter has enough strength to hold the gun and pull the trigger.
-Revolvers can be fired multiple times at contact distance without the possibility of being shoved out of battery.
-A revolver with a shrouded or fully enclosed hammer can be fired from under or inside a cover garment or handbag should the need arise.
-Revolvers are much more tolerant of wide variances in ammunition such as bullet shape and power level thus giving the user more room to tailor his/her choice of ammunition to that which best suits his/her needs.
-Revolvers do not cause bullet setback from repeated loading and unloading as semi-autos can sometimes do.
-Revolvers have a very simple manual of arms which makes them easy to use for people who are not particularly well acclimated to handguns.
-Revolvers can be left loaded for long periods of time (several years) without worry about compression and wear of springs.
-Revolvers require nothing more than the gun itself and loose cartridges in order to made ready to fire (no worries about damaged or lost magazines).
-The grip of a revolver is not limited by the size and shape of the magazine so aftermarket grips can be made in a wider variety of sizes and shapes to better fit a wider variety of shooters' hands.
-Revolvers can chamber more powerful cartridges than semi-autos without being made so large and heavy that they become too burdensome to carry.