Shotguns are usually high risk vs reward weapons.
Especially the Pump Actions (aka the bane of everyone's existence)
Usually only Light Assaults and Engineers greatly benefit from Shotguns though. For the most part, the Medic's Assault Rifles are already really good. But if you have issues with aiming and recoil, try the NS-11.
It's the AR I use unless I'm focuses on the COMBAT portion of the Medic
Basically it has a reliable damage even at pretty extreme ranges, low recoil, and lightning fast reload speeds. Great for playing a versatile support role. Not particularly good at anything though.
Also, you may want to try out weapons via VR Training or the In-Game Trial system.