I bought an 870 Express 12 gauge in 1996 and since then have killed many deer, pheasants, doves, and clay pigeons, and scared the heck out of a turkey with it. I've used it to knock down steel targets in a three-gun match, and I've heard it's a fine defensive weapon. With a ribbed barrel for shot and a slug barrel for slugs, it's versatile, to say the least.
I don't know if it's because it was made a few years ago, but my Express sure hasn't lived up to the bad press that the Express seems to get a lot of on this web site. Maybe I'm just lucky; it's been great. Anyway, it was my first shotgun, and I bought it looking for the same things you're thinking about now.
I have bought other shotguns recently only because my 870 performs so well as a slug gun (with smooth-bore barrel and rifled slugs!) that I'm leaving it set up as such. B-square scope mount and Leupold 2-7x32 shotgun scope, in case you're interested. But that's down the road for you. The open sights on the barrel worked great; the scope's just there to remind me that my eyes are gettin' old.