Well, for tire selection, it's thought that you can't go to aggressive, because you never know when you'll end up where you don't want to be.
ProComp XTerrains, Toyo Open Country M/Ts, BFG M/Ts, BFG Bajas (at $400 a tire though!!!!), pretty much most any mud terrain is desired, but Boggers and Swampers.
If you want an A/T for a particular look or for road mileage, BFG A/Ts, Toyo Open Country A/Ts, Nitto Mud Grapplers, and Nitto Terra Grapplers have all been well proven as well.
I just got a set of Toyo A/Ts for my prerunner :D