I have a 590a1 18.5 with ghost rings and an 870 police magnum 18.5 bead with walnut furniture. Both have excellent +2 extensions and upgraded followers and springs. It all comes down to ergonomics, just handle them and load them and pick which one feels better. I like my 870 for it's classic good looks and no frills and my 590a1 because with the speed feed stock and mesa six shell holder i can grab it and have 18 rounds at my disposal.
If i were you i'd go with the 590a1 and add a hogue forend and call it a day
"Our Country won't go on forever, if we stay soft as we are now. There won't be any AMERICA because some foreign soldiery will invade us and take our women and breed a hardier race!"
Chesty Puller USMC