ok u changed the question sense the first response ive made, 12ga would be my pick.

I had a 10 ga. Thier great if you can find and afford the ammo for them. The price on 410' s isn' t much better.

I like my 12ga. But if it came down to one gun, I would keep a 410.

If I could only get one, it would be a 12 guage. You can always load it lighter.

12 then 410

Buck or Bird...Twenty' s plenty!

12 works for everything.....20 too small for geese but still nice.....10 for goose (I use nothing but and brings' em down hard!) Winner...12

DBL00BK,
If most the folks here were just " shooters" you could ask them their favorite shotgun gauge and it might be straight forward. HOWEVER, since most the folks here are hunters it is only natural for them to qualify their preferences according to " what its going to be used for." It is key to formulate the " thread question" carefully before launching a thread. Even so, a lively thread quickly takes on a life of its own and ceases in rather short order to be the " property" of the originator.

With that said, waterfowl hunting used to be my favorite and I like the 12 gauge magnum (Rem 1100) for " jump shooting" ducks and the 10 gauges for blind shooting geese (Old Ithaca Mag 10 for on the wing and a double barrel with buckshoot for cripples down and trying to get away (4 in a blind, get into a flock, its seldom all clean kills).

Spring turkey appeals a lot in order to put some balance into the hunting year, don' t know which gauge or gun I' d use for that.

Hmmm, Could start a whole new " discussion" here.... but here goes,
Never Go Undergunned,
EKM

I only hunt upland birds, and I do it with a sidelock 20-bore Grulla round body double.

The 16-bore is nice, too, especially when the huns and chukar are spooky or if one of those blasted roosters[>:] decides to make himself avialable.

I own three 12ga' s now, while I' m down to two .410s and two 16' s, basically because it' s stout enough to take anything I want to take, and it' s a whole lot cheaper than my two real favorites, the .410 and the 16ga. I' ve never been a fan of 10ga, basically because the 20ga, let alone the 12ga, can handle everything you could hunt with a shotgun, and 10ga' s cost a bit more for the gun, and a whole lot more for the ammo. I' d never shoot a 28ga because I' m such an avid .410 shooter, and 20ga is just a fun round in between business men in my opinion, .410 does the deed on smaller game and uplands, while 12ga' s do the deed for deer, ducks, and geese. I absolutely love 16ga SxS' s, they' re hard hitting, light kicking and too much fun to shoot, the 16ga has the perfect ratio of kick to knockdown power, the 20ga is a soft kicker, but it' s a soft hitter too, while the 12ga is the opposite, the 16ga has the best of both of them.
.410' s are just fun to shoot, and it sure embarasses my bud' s when I out shoot their 12ga O/U skeet set ups with my baby single shots, either beating them to the trigger, or cleaning up their fouls. I carry less than half the gun, and even though I get half the spread with a bit less power per pellet, I still take more game than all of them every time we go out.

16 ga Ithaca M37 Classic for shot - 20 ga for slug