The Wingmaster is a classic, and it looks better in most people's opinion due to the polished barrel and receiver, and high-gloss wood. It gets an ivory front bead, and a mid-barrel steel bead that the Express doesn't. I just bought a 28 gauge Wingmaster, and it was $599 compared to $289 for the Express.
Also, in the 28 gauge, at least, you get 3 choke tubes with the Wingmaster, whereas with the Express you get a fixed choke; no tubes.
They both will obviously shoot as well as the user is capable of, but for me, I just liked the looks and few extra features of the Wingmaster.
In my opinion, you can't go wrong with either one. They balance incredibly well, point sweet, and last forever.