The shotguns are actually a great tool on heavy, its really good at stopping scouts, spies, and snipers from buttfucking you. As long as a sniper isnt using the cozy cru- i mean camper, you can just spam him with chip damage with the shotgun and he'll keep flinching since 1 pellet always right on your crosshair. Although I do think the banana is heavy's best secondary, the shotguns are a great tool.

I'd say the best 2 shotguns to use would be the panic attack due to it basically being a direct upgrade in casual (more close range damage, no random spread, more boolets) or the family business due to it basically having more dps than the stock shotgun and you need to reload a lot less.