Which one is the best?? Which reduces recoil most effectively?

Snowdog,
I don't know about the decelerator, but the Limbsaver works pretty well with my bum shoulder. Definitely better than the factory pads.

I just happen to have both. The SVL is on a Rem 870 Supermag and the Decelerator is on an American Arms O/U Turkey Gun. I honestly can't tell you if one is better than the other. Both have helped in the reduction of recoil a great deal. The Decelerator seems to have a softer feel than the SVL but I don't know if that translates into better recoil reduction. Hope this helps a little.

I have not tried either one of those, but I have found a slip-on pad called "The Shooters Friend" that I liked so much I bought a second one when I got a new gun. Cabela's carries this pad and it only costs about 15 dollars plus shipping. I absolutely will not shoot 3.5" shells in my pump gun without this pad on the gun. It isn't pretty, but I value performance more than looks. Best of luck whatever you decide.