[Meglobob]

Not the, "best unit" and SP only, but if you get a few barbarian provinces and have a decent nature gem income. Then build a load of barbarian leaders and give them all berserker pelts.

This effectively makes them 99 morale and gives them the +2 berserk bonus at start of battle. They add alot of bite to your armies and are fun. The ones that survive can get heroic abilites, those you may want to consider giving additional equipment too. I give additional equipment to those who get quickness or more hps.

Even more fun is Lychantropos Amulet on your barbarian leaders, its a bonus if any turn into werewolves.

10 berserk barbarians on the right wing and 10 on the left wing with orders attack rear can be very devestating when it comes off.