I when threw all my shotguns, about four years ago, and pattern test them all, several chokes, and multiple loads, lead, hevi shot, ITX and sum steel in the 12ga and 10ga. I used one 10ga, 3.x 12ga, 3.x 16ga, 2x. 20ga and 2x. 28ga.
Think I used up 190 big john targets, sum intresting results, the one 10ga, all the 16ga and one of the 28ga gave the most consistatly even patterns, with my 16ga Fair the best over multiple loads, shots and distance. both 20ga were the worst, with big holes in every pattern, and three inch shells in both 20 and 12ga were often very uneven, I had one lot of 3" 20ga ammo that put 80% of the shot into the top left 1/4 of the pattern target.
all shot 20m and 35M for target distance.
I think that, there is some thing to be said for a square load, and that the old timers, had it worked out pretty well, what weight of shot gave the best, most balanced patterns, the magnum shells, may not be an advantage,
so on that point, a nice 1 oz of #5-6 shot suits me just fine, for most hunting, so 16ga is good for me.