Interesting...I actually have both shotguns and like them both a lot but for separate functions. The pump 870 for home defense and the semi 930 for hunting. If I could only have one or the other, I'd have to go with the pump 870. Have had other semi-autos and experienced at least one malfunction (FTF/FTE or the unexpected double-tap!) with all, never with the 870 pump. Not a big deal when just hunting, bigger deal in self-defense. Love my 930 though for coyote/turkeys! Noticed it seemed hard finding accessories for it right after I got it, but haven't looked lately so probably more widely available now. LOTS of options for the 870. Like I said, love them both but for different purposes and glad I don't have to pick only one. If I did though, pretty hard to argue against the venerable 870 pump!
If you wanna run with the big dogs, you gotta get off the porch!