J-man,
Since a sidearm is a last ditch close quarter personal defensive weapon, I see no problem allowing every service man/woman in providing their own.(very cheap solution too) Encourage regular training and familiarity. It would be the best option for most people. The choice of a sidearm can be a very personal preferance thing. For example, I hated the Browning HP, and found the grips and trigger pull way too big and long for my hands, However the Colt 1911 was a perfect fit. Despite that my prefered pistol (until my hand was damaged) was always a revolver. Most troops are not even allowed to carry a pistol (stupid regulation) and don't get issued with one. If it breaks, pick up another, if you have done your job right there usually a few lying around (Joke) ;-) Of course ammunition supply is always a problem, I doubt if the military will supply anything "out of the ordinary" so it can be problematic supplying various calibres. So ammo has to be regulated.
This is a hypothetical discussion, as carrying a personal choice weapon will never occur in the dictatorial bureaucratic world we live in. My heart is with the troops, I would let them have anything they wanted. Stay safe, and hope you don't need to use yours!