Looking into getting a new shotty, I know most people say Remington, but why? Are the mossbergs not reliable or durable?
No, it has nothing to do with the single action arms of long long ago and everything to do with fit of the dual action bars and forestock. The 500 is loose. The 590 is a bit better and about equal to today's 870 express but not fully. The Wingmaster is 4 times the gun of any of them. A used Wingmaster is the best value of any gun made in America today. In the end any 590 or Express combo will cost about the same as a used Wingmaster.Here's an extensive thread on the subject that you should read also.
https://www.indianagunowners.com/forums/long_guns/245997-can_a_pump_shotgun_guru_explain.html
ETA: I think the rattle that is being highlighted harkens back to the day that Mossberg had a single arm in the action vs. newer models have double arms, IIRC.