I have the Mossberg 500 and the Remington 870, similarly configured, and I prefer the Mossberg. But I like the Remington too. They are both fine, I think it's a bit like what ice cream you prefer, vanilla or chocolate.

As far as the Knox recoil pad...I don't really think that they are needed, but some folks swear by them. I guess it all depends on what you like. I don't mind the buck of a 12ga, my wife didn't like it, so I got her the Mossberg 500 in 20 Ga - at 15 feet, 12 or 20 ga is going to put a hole in anyone, so it's not a matter of one or the other being a better "stopping" weapon, it's a matter of which one you can actually USE.