Smoothbore, yes?
Rifled barrel, yes?
Here is my take,
Slugs have a place in smoothbore shotguns whether for defensive purposes or hunting, but you have to understand the limitations of the system. Don't think of it as a precision instrument. It is not and will not be a rifle, and if you enter into it with the mindset that you'll get rifle like accuracy you will likely be sorely disappointed. For smooth bore shooting "rifled" slugs think 50 yards as your effective range based on accuracy. Your effective range based on terminal performance is much farther, but your cone is big at 50 yards and even bigger at 100. 8" Vital zone on deer translates well to center mass hits on 2 legged predators. Break out some paper plates and a couple brands of slugs and see which ones stay on the plate at 50.
FWIW I've had the best and most consistent results with Brenneke KO and Federal Tru-Ball. That is in mostly Remington 870's, 11-87's and 1100's with smooth bores and either Cyl or IC choke. I've had a couple rifled chokes and not really cared for them. I've had a couple rifled barrels and, same...... 3-4" at 50 is good enough for me.