Quote Originally Posted by Fao View Post
Legendarys also add to all your stats more than epics do. So, Legendarys will maybe add to mana regen, health regen, Dex, crit, and more, while epics add to only a few, or if the same amount, not as much as a legendary would.

Legendarys of a full set can also provide a set bonus. So the helm, armor, and either 2h weapon or 1h weapon + the shield. Like ThePvPTwink mentioned, it also gives you a cool look!
That's not always the case though, Epic items can sometimes have the more beneficial stats for your class. Rares too, sometimes.

It is true that only Legendarys can make sets though.