Benelli in my opinion. Much fewer parts and very easy to field strip. Never seen a Benelli fail on any duck hunts. (I just jinxed myself and my gun will fail now) This includeds being dropped overboard, covered in mud from laying in a wet field, bouncing around in a bottom of a boat, fine dry silt blown into everything (this causes the most problems) and everything else you can imagine. Have seen all the other brands of semi-autos fail at one time or another.
I don't know about the new guns but the older blue finish was not very good. It tended to get a lot of surface rust on it quickly but easily wiped off. The camo finish seemed much more durable.
However, if you are planning on hanging a bunch of tatical stuff on it go with the Winchester. The inertia system is not tuned for extra pounds. Benelli also kicks slightly harder and is a little lighter than most gas driven semi-autos.