I've had considerable success with the 15 round packs of Winchester Foster Slugs. The Brenneke K.O. slugs worked very well also, but I've not been able to find any lately (but they aren't Foster slugs, so that doesn't really matter). I save the Magnum slugs (esp. the heavyweight Federal slugs) for when I'm hunting bear. They have a tremendous extra bundle of recoil--but they are much heavier, so it's no surprise about that.
The Remingtons and Federals shot about the same, with the Winchesters edging ahead slightly. ALL three brands were plently good for hunting. Most people don't practice much with their slug gun--which bluntly, is kind of dumb! If the recoil is that bothersome, then maybe something less noticeable should be used. I have the option of using a rifle in my State, but the heavy cover & close range where I hunt is perfect for slug use. It makes lots of sense to find out what works for you and stick to it (as long as you're able to find them to buy anyway!).
Good Luck and Shoot Safely!
WV_Hillbilly