I sell (at work) just about every pump shotgun currently available.
I also own an 870/12 gauge (20'ish years old) and a PA-08/20 gauge (just bought it a month or so back).
NEITHER is the most popular seller in my experience - we sell three or four Mossberg 500's or 535's for each 870 and a couple 870's for each PA-08 (which sell about as well as Winchesters and Brownings).
Unless you are looking at an 870 Wingmaster I might tend to stay away from a new 870 Express - the machine work, fit/finish and (meshing) of the parts on assembly leave a lot to be desired - and if you think a synthetic stock is superior because it won't warp or twist, Remington has found a way to produce them "warped and twisted" right from the factory.
I assemble many dozens of shotguns and the only thing more difficult to get together, from the box, than a synthetic 870 is a synthetic 877 (which are just downright horrible) taking significant pressure and twisting to get the barrel to mate with the receiver.
The PA-08 for fit/finish/machine work mirrors the 870 Wingmaster (at half the ticket price) and the Winchester SXS which is also a nice shotgun (right out of the box). All of these assemble as if the parts were "hand fit" at the factory.
The Mossberg's generally assemble without significant issues - their one problem is the camo on the barrels extends to the part that goes into the receiver and needs to be cleaned up a little to prevent sticking when trying to remove the barrel.
If I was looking for a NEW "entry level" shotgun today, the 870 Express would not be on the list. If you are looking for a NICE wood stocked shotgun then the PA-08 is the hands down "best value".
If you are looking for more "multi-purpose" in a synthetic I would go for either of the 3 barrel combo's offered by Mossberg. These are "dressed" in one of the Mossy Oak camo patterns.
They come with a 28" Vented Rib barrel (plus 3 chokes - I/C, M, F), a 24" Turkey barrel (with extended Extra Full Turkey choke) and a 24" Fully Rifled Deer barrel (with cantilever so you can mount a scope).
The 500 Model (3" chamber) is about 75 bucks cheaper than the 535 Model (3 1/2" chamber - or Super Mag if you like) - sorry could only give you Canuck price ranges, but the 535 combo sells for the same price as an 870 Express Camo (which only has 1 barrel and 1 choke), with the 500 combo selling for about the same as an 870 Express in either wood or synthetic.
The Rem 870 only comes with a modified choke (so out of pocket if you want something other than Modified).
The Wby PA-08 comes with three chokes (I/C, Mod, Full)
And although I have (bashed) the new 870's a bit here I have never had complaints about their function. Also there is one currently on the market called the 870 Sportsman Field. It has a 28" VR barrel and a Mahogany stock. Sells for about the same price as the Express models. It went together nicely and the wood and checkering is very sharp looking. If I "had to have" an 870, the Field model would be the one I would buy.