3. Barbarian
I love me a good Barbarian class, the big problem here is how gear dependent he is. If you don't luck out and find good weapons, you'll feel very underpowered. If you find something good, or have something good muled away, then the Barb is a blast. Early on, having a Barb meant you had to get a good drop or trade with people, which was fine, but it was just easier to grab a MF class and farm for your own stuff.
You then pretty much have stuff waiting for your barb, which detracts a bit from the experience of getting loot. Iron Man Barbarians could be intensely frustrating to play. There was also the issue of "what mastery do I pump up?" if you weren't muling over weapons.
That all said, Barbs were machines, WWing through everything, and I loved Frenzy builds nearly as much. Hell phys immunes definitely drag things down, and while Berserk gets the job done, it's no fun. But caving in everything else with a good piece of steel is just grand, and PvP was also a good time. A lot of WW duels just came down to "who hits WW at the perfect time" as well as pulling off perfect triangles, but group play was a bit different. You got your hands on other classes and they were often toast, but you had to figure out how to get there.
A classic and basic melee class (unless you try throw Barb), but still just an amazing romp.
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Donny: Are they gonna hurt us, Walter?
Walter: No, Donny. These men are cowards.