I've owned all 3 and can't say any of them were bad. The only issue I ever had with any of them was infrequent short stroking which was my fault and that was with my Rem 870 HD (with the stupid mag tube detents).
Of the 3 I actually think the Winchester had the slickest action of the ones I owned, possibily due to the rotary bolt. It seemed the easiest to shoot fast although again, none were bad.
A couple of things to keep in mind on the Mossberg 590's:
- the military 590A1's are built a little sturdier than the commercial 590's. They have a heavier barrel (FWIW), a steel safety and an aluminum trigger gaurd whereas the commercial 500's and 590's have plastic trigger gaurds and safetys.
- the 590's also beat out the Remington and Winchester in the military trials being the only pumpgun to meet of exceed the gov test criteria (3,000 rounds without a malfunction I believe it was?). It's the currently purchased and issued shotgun at least until the semi-auto Benelli M1014's work thier way into service. there are still 870's and Winchesters in inventory but all purchases in recent years have been of 590's.
In Winchester's, check out thier "Camp Defender" model. Interesting setup IMO. 22" barrel with screw in choke tubes, rifle sights, synthetic stocks and matte finish and a 7 shot mag tube. Cost is only about $250 and if it worked as well as my last Defender I wouldn't have any gripes with it at all.
http://www.winchester-guns.com/prodinfo/catalog/md1300/13cmpdef/13cmpdef.htm
Keep in mind too that, FWIW, FN markets the Winchester 1300's under the FN name in thier law enforcement line. Again, a nice setup IMO, 18" barrel, 7 shot tube, rifle sights and screw in choke tubes.
http://www.fnmfg.com/lawenf/shotgun/shotmain.htm
I'm sorta in a similar boat as you, I have an HD shotgun (the 870) but would like to get something with a full length mag tube (for no other reason other than I want one, I'll still probably use the 870 as my house gun). I've been kicking it around for a while and am finally ready to buy and my choice is down to either a 590A1 or a Benelli Nova Special Purpose with a mag tube extension (7+1 capacity). One bonus the 590 does have when it comes to pi$$ing off the anti's is the bayonet lug. Nothing gets Chucky Schumer and his ilk more worked up than an "evil" miltary feature
.
In the end though Dave's probably got the best advice: shoot a variety of stuff and get what you like best as long as it's reliable. We're all going to have individual prejudices and preferences but you're the one who's going to actually end up with the shotgun so get what you're most comfortable with.