Great question! I didn't vote on the poll as it really depends on the person. I own/use both an 870P and 11-87P. Some pros & cons in no particular order:
-my 11-87P's reliability has been fine for 1,000 rounds (est'd). Clean and inspect the o-ring after shooting everytime. That's the maintenance. If cleaning and inspecting is not one's "thing", then go toward the 870.
-many on this forum are expert shotgunners shooting thousands of rounds in trap/skeet/clays etc. These folks experience o-rings degrading (high round count & age) on 11-87s. Most will not have this problem.
-I mainly see cops and regular novice folks at the ranges where I shoot. The more common problem with pump/870 failure is short-stroking (also stance). Again, the experts here do not encounter this problem. The person who doesn't plan to practice or shoot much may have this problem. In this case, a semi will be better.
-For home defense, the ammo is likely going to be something like 00 buck &/or slugs. By all means, test any ammo loaded/fielded in one's shotgun, but generally these ammo types will function fine in the 11-87P and, of course, the 870.
-For semi-auto pistol shooters, the 11-87P may also be more familiar. Chamber the round; shoot until bolt locks back. No need to pump with authority. This is an over-simplification in shotgun training, but, practically speaking, not everyone will be getting this training & practice of moving, shooting, loading, and ammo selection of buck to slugs or vice versa.
-the 870 generally will run and feed most anything, especially if a lower powered, low recoil type round is going to be used. For HD and using a semiauto, the lower powered stuff is probably unnecessary, though. Using a Wincheser, Federal, Remington, or equivalent 2 3/4" 00 buck should work fine in either gun. Again, test ammo before fielding.
If the original poster is comfortable with both platforms; knows he'll do the maintenance; then choose either gun. Can either gun shortstoke or be shortstroked? Sure. Shoot enough to experience a malfunction but also shoot enough to readily clear the malfunction or automatically transition to handgun and I think we'd be getting to where we'd ideally need to be.