The 870 Express and the Wingmaster (at almost twice the cost of an Express) are NOT the same gun in terms of fit/finish. The 870 is still the most "sold" pump shotgun on the market. Doesn't make it the best, just the most popular. We sell a lot of them, can't say I have had even one owner come back looking for service/warranty.
I had a bad experience with Winchester customer service back in their dying days which soured me on everything Winchester, but have to say if my only current choice was between an 870 Express and an SXP I would lean towards the Winchester (which yes, now, Winchester's parent and Browning's parent is the same company - but that's where the line crossing stops - the SXP is built in Portugal with mostly Belgian parts from the parent company Herstal/FN).
The fit/finish on the SXP is (my opinion) superior to the 870 Express - plus, with the Express you only get a modified choke - Winchester throws in an I/C and Full as well. Not a big deal, but you don't have to pay for the two extra chokes and the two shotguns are generally priced almost exactly the same.
As has been suggested you may want to look at one of the various Mossberg 500 combo guns. There is even some of the model 535 3 barrel models still on the shelves (28" VR barrel, 24" Turkey barrel and 24" fully rifled deer barrel) for maybe 100 bucks or so more than most of the Express options.
You have to compare apples to apples if you are in the market for a NEW, entry level pump shotgun. Many will say that the new 870 Express are junk compared to a 20 year old model - maybe so, but in today's market the 870 Express, SXP, Mod 500, plus the entry level offerings from any of the other majors function "just fine" - it's more of how it feels in your hands than any great advantage one to the other.
I would add one more to your mix to check out if you are still "looking". Have a look at the Weatherby PA-08. Priced competitively to slightly less than the others, excellent fit/finish, 3 chokes included.
What I have noticed, since I assemble many many shotguns for the gun racks is that despite all the "perceived advantages" about synthetic stocked guns (if you are looking at the synthetics vice wood) is that for all the "will never warp" in the selling points, Remington has found a way to produce "warped" stocks. Many of the Synth Express models take significant pressure/twisting/shoving to get the barrel to seat properly the first time they are assembled. They seem fine afterwards, but that tells me they are somewhat "stressed" right from the factory which kinda throws the "will not warp" theory right in the trash from the get go.