For parts availability/aftermarket products go with a Remington 870 or Mossberg 500/590.
If you want a light on it I would suggest spending the money on a fore grip that has the integrated light (SureFire, Streamlight). I have tried many light mounting options on shotguns, and none worked out as well as the integrated style for form and fit.
For your proposed application I would furnish either with a 14" - 18.5" barrel (with the Moss 500 you will need an entire kit to have a 14" barrel unless you buy the one with a 14" barrel).
I would love to get my hands on an old Surefire forend for my Ithaca.
I have heard some say that the newer Surefire are not worth the trade off due to the weight and that they’d just add a simple flashlight. I really cannot comment. I do have a 2nd Gen Surefire but I’ve never mounted it on my 870 so i can’t really compare the weights. Certainly the most user friendly option.