Well, I have hunted both, and my best suggestion is slugs. They are a little more predictable then buckshot in my opinion. Basically, the best thing to do is to get several boxes and shoot it at a target. Aim good and see what happens, It should group pretty good I would think, just base it off of that. Make sure the shotgun is able to shoot slugs though, don't pull a stupid move and run a slug through a full choke, you will regret it. My buddy did it once on an old single shot, blew the living tar out of that barrel and he thought he was certain to die.
F-C