Separate names with a comma.
If you can afford it, M4, no question. Now that's a shotgun.
Do you enjoy driving the Jetta or would you prefer to drive the AMG Mercedes? Either one will get the job done. The Benelli is an incredible shotgun, just really expensive. I can do everything that I need to do with a Mossberg 590 or 590 A1 at half the cost.
Without the addition of tripwire and hand grenades you won't even be near safe.
Another consideration is how much do you plan on shooting it? Are you going to shoot/train with it regularly or are you going to buy it, shoot it once and lean it against the wall in your closet? How much do you really need to spend on a wall ornament?
Three words: shu ri ken.
Another consideration is what kind of invaders do you anticipate?
Just a consideration- Do you really need a semi-auto shotgun for home defense? Other than name, I can't think of a good reason to go outside of Mossberg or Remington. When police, prisons, and worldwide militaries use them, I can get behind it.
I'm planning for counter home invasion type defense, m4 is probably extreme but Benelli seems to be respected quality even over Rem and Moss, and the Nova competes at that price point.
Benelli is absolutely a strong name and I've never heard negatives about the nova or supernova. The plus for 870 and Moss 500 is the unlimited peripheral market. I don't think you'd go wrong with any of them. The M2 is half the cost of the M4 if you wanna go that route and it's often said to have a more dependable firing system.