Remington/Mossberg/Benelli Nova Youth

I have a nine year old boy that is average size/build. I'm looking to purchase a 20 gauge shotgun and looking at the Remington 870 & 1100; Mossberg 500 youth and Benelli Youth shotguns. What would you recommned. I don't want recoil to scare him away from a great sport.

I appreciate your input.

David