Sorry, but I'm going to add to the 50-50 problem. I have both. I first bought the Nova combo with rifled cantilever deer barrel and bird barrel with 3 chokes. Got it for $400 BNIB, a real steal. It's almost impossible to find just the cantilever deer barrel for that price. My ONLY complaint about the Nova is the weight. The 3 1/2 magnum chamber makes it just a bit heavy. But I have no qualms about taking it out in the nastiest of weather. I'm typically also not a fan of the 'one-piece plastics' as someone else said, but I really like the feel and fit of the Nova stock. The weight might not be as much as an issue with the 20ga, but I only have the 12.

I subsequently got a used 870 with a cantilever rifled barrel and outfitted it with a Boyd's Thumbhole Stock and it is now my absolute go-to deer gun. I picked up a used bird barrel for the 870 at a great price, but have not tried it with the thumbhole stock. I'm just not sure how the thumbhole will work with wingshooting.
My son has the same thing in 20ga, and it too is a great setup.

They are both great guns, I'd personally go with what fits and feels best. That is ultimately what matters most, IMHO.