I was thinking about the Mossberg 500, but had my daddy buy me the Remington instead. It's better made. Steel receiver is much more durable and the fore-end rattled a lot less. Mossberg 500 does have a good design (I like it a bit more than the Remington design), but the workmanship and materials are simply not as good. I have a FOID card in this state, which allows me to own a long gun (despite being 16 years old) and handle them at stores, so I got to see a whole bunch of stuff before I decided.
The finish on the Mossberg 500 beats the Rem 870 Express finish though. You get a good blue instead of Remington's crackly black finish that they use on the Express series.
If you wanted to use a gun for home defense or as a fighting shotgun, some people would say that Mossberg is better because of the better safety, ease of reloading (Remington's elevator/carrier slaps me in the thumb hard), light weight, etc.
I didn't get my gun with any fighting of any sort in mind (sometimes I think I'm almost pacifist). I wanted a good hunting gun that would be reliable, and so I got the 870.
During the time I was considering the Mossberg 500 (the Dick's Sporting Goods exclusive model with the wood stock, barrel, long vent rib barrel with extra chokes for all sorts of hunting), I asked a friend what he thought of the Mossberg and he said it was a "cheaply made piece of crap." With all the choke tubes and nice finish and wood, all for $200, it seemed like a hell of a deal for a all-around hunting gun, but it is sort of cheaply made (and cheaply priced). Appeals to sort of different customers I guess, some want the best deal, while others want the better gun for a more money.
[Edited by Chang on 01-04-2001 at 08:27 PM]