I use standard steel 3" for ducks and geese.
Pattern 1 from each load with each choke at 40 yards.
Unless something unusual shows in the patterns,
I will tend to pick an IC choke over decoys and
the smallest shot size that will completely penetrate (i.e. go all way thru!)
as I don't want to "find" steel shot in my duck or goose meat!

at 40 at less yards:

#4s for small ducks
#2s for big ducks
#1s for small geese
BBs for big geese and cranes

Especially for geese, I put out a 40y yard marker.
When I get use to judging distances on ducks,
I'll judge geese closer than they really are!