Spanky,
I have owned and/or shot all of these. Mostly I shoot them for fun, some for hunting and in competition. Others defensively both as personal protection and as tactile weapons. All will serve the average person. As much as i like H&R's I dismiss the Chinese immediately as I prefer to buy American. I do not like the non steel receiver and plastic fire-control of the Mossberg. I choose the Remington 870. Defensively my first choice is my Remington 870. Defensively, I actually prefer it to my other favorite a Colt .45 Commander.
Like Andy, (MSP ret) mine too is as much a familiarity with it, having trained with one and shot one so much its an extension of me.
I think you know, have been in the firearms industry in some fashion, for many many years. I see them all the time, mostly going out as new or used firearm purchases. But occasionally I also see them coming in for repairs. I see far more Mossbergs coming in for broken safeties and fire-controls than any other shotgun problem. One good thing was that even broken, the gun could easily be made to still work. When the military took the Mossberg, it required the 590 (Basically a tactile version of the 500) to have steel parts exchanged for the plastic junk on civilian models.
MANY years of experience out there for the Remington. This serves you because most gunsmiths will have worked on or with one. Many many manufacturers have or make aftermarket parts and accessories for the Remington.
Remington's have flatly proven themselves many times over. they are THE pump shotgun ALL others are judged by.
Back when the Benelli auto shotguns where gaining a foothold with police and sportsmen. I was at a police training event. A good friend and I where there as "ringers" shooting on police teams as civilians. the match when on and when finished we had a little competition. Now everyone was SUPPOSED to be shooting service weapons. Seems everyone had a supped up Benelli. I was shooting a Remington 870. We did VERY well finishing in the top few shooters. I finished top time in pepper poppers at 10 yards, by over a half second!! I tried to beat my own time with a Benelli... I couldnt do it!! I was shooting my 870 faster and more accurately than younger shooters shooting a so called "better" shotgun. In the hands of a experienced shooter, nothing is faster than a well tuned 870.
There is only a few things I will stake my life on, one is my Remington 870.
CW