If it were me I'd opt for a 3" .357 Magnum loaded with Federal 357B and never look back.
"Muzzle Flash is a Range issue", as Evan Marshall likes to say. "You will not notice it in a gunfight." My favorite caliber, bar none, is the .357 Magnum. It has versatility that other calibers don't. The caliber has been used to take every Big Game Animal in North America and is the self defense caliber all other handgun rounds are compared with. Nothing has bettered it in all these years.
Why I would choose the 3" gun over a shorter or longer one?
That's easy. The 2 1/2" gun gives up a little too much in velocity and has too much unburnt powder. Hence, even more muzzle flash. The extra barrel legnth on a 3", even though only half an inch, does seem to make a difference in that Range Issue. Also, the 3" gun carries like a 2 1/2" gun unless you carry on your ankle or in your pocket.
It has been said that the 3" Gun shoots like a 4" gun, and I agree. The longer sighting plane is an asset to longer range shooting and accuracy. The 4" Gun is a good compromise for Open Carry/Concealed Carry, like a LEO carrying his or her duty gun off duty.
If you will note, back in the day, the F.B.I. issued a 3" Model 13 to it's Agents. They found that the gun shot like a 4" one and carried like a 2" one. I think I already mentioned that, didn't I? S&W makes a 3" .357 Magnum and so does Ruger. Of the two I went with a Ruger because I like to shoot a lot and while the K-Frame carries well, it doesn't handle a steady diet of .357 Magnum loads well. The L-Frame has an adjustable rear sight, while handy for Range usage, I prefer fixed sights on my defensive weapons.
I shot over 800 Rounds of "full house" .357 Magnum last year out of my Ruger GP100 3" Model that I had "tricked out" just a little. It's DAO with a "bobbed" Hammer and a Hi-Viz "type Front Sight.
I don't think you'd go wrong with a 3" gun, and if you can't tell, I'm a fan of them. I stopped carrying my 3" Revolver to carry another "classic" off duty. I currently carry a High Power, but in .40 S&W. Revolvers, 1911's and High Powers seem to do it for me. There is nothing wrong with a good revolver and I would gladly carry one on duty if they let me.
Biker