Mossbergs feel a little cheap to me when you cock the action. I love my 870. There are tons of accessories for both. A lot of the accessories are worthless especially the Barrett style muzzle brake on home defense mossbergs.
I picked up an 870 Friday from Dicks for $289.00 OTD. It is parkerized with a 26" remchoke barrel. I plan on getting an 18.5" for home defense. I haven't shot it yet but it feels like a solid gun.
either one will solve any problem you might run into. but i would lean towards the mossberg. it's more heavy duty in build, has a better safety location and slide release location. it has a metal trigger group housing and you can't forget it is the only one of the two that did pass the mil-spec. for what its worth.