and to make it more complicated you cannot buy into the Cylinder, improved cylinder, modified, full, extra full, cause they have different diameters from different companies. The names "Turkey choke" are equally meaningless.
You must pattern your gun with your choke and your load to know what is happeninG.
But to step out on a limb. Modified is the most universally useful choke. Cylinder is basicly the 12 bore, improved slightly tighter, Mod slightly tighter, full extra full etc.
Carl