The best gun is the one that fits you. Shotgunning is fast. There's no squeezing the trigger or aiming the gun. It has to set immediately to shoulder and should have a natural point of aim.

The 870 is a nice starter gun. The Express is the cheaper gun compared to the Wingmaster. The finish isn't as nice and tend to rust (more than usual). I prefer to use an O/U for upland but when I did waterfowl, used a 870 12ga. The O/U I use is a SKB (Japan made) in 20ga. The only reason I don't use the 870 is simply because I prefer the 20ga but wouldn't hesitate to use the 870 if I still shot 12ga.