Theory crafting
Being able to choose my own stats and skills as a somewhat meaningful decision.
I like that your monk and my monk are exactly the same, like clones!!!!!!!
2 handed witech doektor pew pew fire bats stronk
Who can forget Magdha. The butterfree villian who killed Dekkard Cain because fuck it.
Just the overall story in general, it's a masterpiece. Azmodan telling me his battle plans constantly via drug induced hallucinations. Diablo's tits.
Trading
8 players in game.
Dueling / hostility.
Fun.