5s. By far. Im assuming pointing dogs? If not then bismuth would work betyer. But you will never need 3 inch for pheasant. Been hunting them 30 yrs, and nope never.
Just a bit of advice, they arent sporting clays or a really good dove shooting gun. You will be brused after a 50 or more round shoot. Love them for game but not a bunch of shooting at once.
Im a pointing dog guy . They usually are out front and find birds that a flushing dog hasnt got to yet but as far as tracking I would say that the flushers would have that advantage. Theres room for both for sure. My friend has added a lab to his string of pointers and setters. Its worked out...