20 for all the above reasons.

20 , but I love my 28

Why an O/U? Seems like a perfect scenario for a pump.

My reason for a double (either O/U or SxS) is three fold. First, 2 chokes instead of 1. Can be an advantage in hunting situations when game presents itself at any and all ranges. Second, ability to have two different loads at your disposal without having to rack a round out of the chamber. For instance, if hunting small game but also may encounter something bigger I might want to shoot such as a coyote, I can have smaller shot in one barrel and larger shot (buckshot) in the other barrel and can immediately choose the load I need when the opportunity presents itself. Lastly, if you reload or just don't want to hunt for shells to avoid littering, it is much easier to recover your shells with a double.

I suppose those rationalizations look ok on paper. I’ve probably used those arguments myself in an effort to angle for a new gun. I’ve never gotten around to loading two different types of ammo and my barrel selector hasn’t moved since I bought any doubles. Having two triggers on my side by sides makes barrel selection very easy, yet the front trigger gets pulled first every time. There could be a case for recovering empties. We can all stand to do better at keeping nature natural.
Definitely get the 20 instead of the .410.

They also work good in the squirrel woods. If I'm hunting with a double gun, I always use a light load/open choke in one barrel for close shots and a heavy load/tight choke for long shots, to good effect. That said, a pump or autoloader with modified or improved modified also works very well.

Also check state game regs for having correct size shot shotgun shells for game hunted. Some states small game-furbearer require #2 or smaller size shot. Having buckshot out of big game season might be frowned on.

Good point as some states have stupid laws on the books. In Missouri, no law limiting shot size on coyotes so buck shot is fine. #4 buck is used by many folks out here.

I killed tons of squirrels, rabbits & marsh hens as a kid with my .410. It did fine as long as the range was modest. I didn't have such great luck with doves. Then Pop started letting me shoot his old lightweight 12ga. LC Smith bird gun. I remember thinking, I can actually kill flying birds with this! Most folks find it hard enough to kill doves with a 12 ga.! When I was a kid, the standard 3" .410 load was 3/4 oz.,(now 11/16 oz.) with 7/8 oz. for the 20. The 20 is much more effective with it's 7/8 oz. load than the .410 with 3/4 oz.. It is not a linear relationship. The 20 is more efficient for a number of reasons, it patterns better for starters. I have always wanted a 28 ga. SXS but it looks like that will never happen. I never shot one but folks tell me it is closer to a 20 than a .410. I have 20's, 12's & 10 ga. guns. I have killed more game with my 20 ga L.C. Smith than all the rest combined, including big ducks & pheasant. I can score almost as good with it on doves as I can with Pop's old bird gun. Pop is gone but I still shoot his old bird gun. I don't know what the weight difference between the 20, 28 & .410 usually runs but I never heard anybody complain that a 20 was too heavy. Should you want lighter loads, the 20 will accommodate you if you reload. 20 ga. 3/4 oz. load data is not hard to find if you want it. My standard go to load for the 20 is 7/8 oz. but I have used the 1 1/8 oz. loads. I have two 3" 20s but haven't popped the cap on a 3" 20 since early 1970 something nor more than a half dozen in my life!

HuntingDixieLand,

Good advise given here already, I will add this for you to think about. The .410 is a good gun for dog training, however for Dove shooting the 20 gauge is a lot more versatile and if you want to make it even more sporting I agree the 28 is a great gun. Although the 28 is going to cost you more money, both for the gun and the shells. The 20 gauge is less expensive all the way around, and gets the job done well.

Pine Creek/Dave
L.C. Smith Man

Absolutely a no brainer. 20 gauge.

Of your two choices I would recommend a 20.
But Im with one ounce