870
I don't think that the 870 is actually BETTER than say, a Mossberg 500. But, since it is (a) equally good, which is to say very good, and (b) there are more aftermarket doodads/customizations than other brands, (c) LEOAs overwhelmingly prefer them (for whatever reason; probably mostly due to good price), and (d) they are famous for their many excellent rifles as well (unlike mossberg or winchester) they get a reputation that is more than the sum of the parts, and it's a vicious cycle / self-fulfilling prophecy kind of thing going. The rich get richer. Still, it's an excellent shotgun!