I bought a Benelli Nova many years ago and I use to shoot Trap and Skeet with it, until I got an O/U shotgun for clay shoot, so it has been retired to home defense. I love the look of the Nova, but I have no experience with the SuperNova or the Mossberg.
In regards to your question, it depends on what you can afford and which one has the features you are looking for. Also, which one can you customize more?
Even though I have a Benelli, I'm leaning towards the Mossberg. You can customize it pretty easy.
A few others have mentioned it, even though you didn't ask about it, but I would go with the Remington 870 over the two you mentioned. Just my personal pick.