While I have quite a few semi autos IMO the biggest advantage of a 9mm semi auto is capacity , otherwise I prefer a .357 revolver.

Revolver advantages are safety and reliability , (I actually know a guy that forgot he had a round in the chamber of his Glock and shot himself in the leg while cleaning it),
Also if you have a bad primer or dud in a revolver you simply pull the trigger again and it goes BANG, revolvers do not have the inherit FTF, FTE, stovepipe or feed ramp jams, reloading is not affected by limp wristed shooters, they are not finicky loading hollow points , you dont have to worry about weak mag springs or having your magazine fall out in the field,
a .357 is more versatile since it can fire .38 special on the range which is fairly close to 9mm ballistics or .357 Magnum for self defense which is hotter than .40 S&W and even 10mm.