I don't know, I like crossbowmen the most, and also wolves... Crossbowmen are good throughout the game and often remain the only ranged units in the Haven army (ballista is slow, you can't carry it around, and monks lose to crusaders and lack accuracy), and shooting without penalties is a big advantage.

Wolves are also strong, with good speed and 2 attacks, and unlike berserkers, they are tamed, so you can accumulate a good number of them, and in large quantities, they will deal good damage and remain useful.