As an owner of a Mossberg 500, the only pro I found with the Remington 870, and even more so with the Winchester 1300, which I prefer greatly to the 870, is the ease of racking the slide.
With the Mossberg, it's not too smooth and pretty herky-jerky. The Winchester 1300 slides like butter and the Remington comes in at a close 2nd.
If I were to do it all over again, I'd still buy a Mossberg for home defense but, for targets, I'll take a Winchester 1300 any day.