Sylvain has a point.
But I gotta tell ya, if I were a decision maker for a department, I'd let them pack whichever they preferred. Or both, if they wanted.
Our local department (actually part of the military) has access to submachine guns and full-auto rifles.
They still like to bring shotguns to traffic stops for the deterrence factor.
Here's what they use.
Some people complained that they use the standard issue guillie suit to hide on the side of the road with a radar gun, and it wasn't fair.