Pattern the choke on cardboard / paper at various distances and then you will KNOW the best range.
I'd recommend getting one that patterns well out to 40 yards.
Remember when shooting steel shot, it's like one more choke size (IC with lead is like Mod with steel).
Their descriptions might be with different shot size than you plan on using - It's a general guideline; no more on less.
You need to pattern your gun, with your choke and with the shot size you plan on using (20 yards, 30 yards, 40 yards, 50 yards) !