I love the Gallic Swordsman, had a great time enslaving barbarians (and Incans!) with the Javelin Thrower, and thought the Samurai was pretty dominant (not to mention have a kick-ass animation).
However, I never rampaged through the enemy like I did with the Berserker. I went from a struggling fledgning Civ to world power as my Berserkers sailed up and down the coasts, grabbing cities left and right. Way too cool...