No doubt the 12ga is effective, and the 870 is well-proven.

My only experience shooting a shotgun was familiarization training with the 870 during a LE course I attended (I am not LE, just took the course). It was a plain jane, wood stock and fore-end gun with a bead sight. All ammo was 00 buck. 2 hours learning the manual-of-arms, loading and unloading, shooting, etc. I can't remember much about shooting it, but we did some quick wing-shooting (stock tucked under the armpit) and I remember not liking it. It was also challenging as I'm right-handed/left-eye dominant and was shooting the gun as a righty. If I do ever get into long guns, I'm inclined to shoot them as a lefty.

I remember the instructor telling us a story about a police officer who tried to use the stock to help boost his partner over a fence or wall like he had with a M1 Garand, but because the stock was just attached to the receiver it ended up breaking.

Not too long after the class (this was probably mid-90s) I visited a LGS that had a bunch of used LE 870s for sale. I can't remember the price, but I remember thinking it was a very good value. I was very tempted to get one, but didn't.

Nowadays, when it comes to long guns, I'm much more interested in getting a pistol caliber carbine (PCC) than a shotgun, but there are times I'd like to add an "old school" shotgun to my meager collection, probably an Ithaca 37/87. Or maybe a short-barrel side-by-side coach gun like the Stoeger.