870's can do the job just fine but, in my evaluation, the controls ergonomics on the 500/590 are quite superior....
Here's why I love the Mossbergs and recommend them over the Remingtons:
Let's start with the ACTION RELEASE... while holding the gun ready to fire, to cycle the action all you need to do is shift your second finger slightly from where it already is and push up, without changing grip or other fingers at all, and it's done. NICE!
Next up... the THUMB SAFETY, again while holding the shotgun ready to fire, the safety can be flicked on and off readily by the thumb (and is visually very clear as to what position it is in) without changing your grip or fingers at all. VERY NICE!
Now, moving on to the LIFTER... when the gun is ready to fire, the lifter is up and out of the way, allowing topping off the mag without having to push the lifter out of the way. AWESOME!
Additionally, the 500/590 has TWO EXTRACTORS. REASSURING!
Mossberg really thought through the ergos on the controls much better than Remington did.
Of course a shooter can learn and acclimate to either gun and both the 870 and the 500/590 are excellent and worthy shotguns which will do the job admirably. That said, my recommendation is to pick whichever one feels better and more ergonomic to you, go with that, and you'll be fine. My choice is clearly Mossberg; my long-term standby 500 Persuader is a super-sweet, rock-solid, dependable 18" 6-shooter and I just added a new 590 20" 9-shot which is every bit as great, but with more capacity.