Which installment of the Heroes series had the best campaign storyline for you?

Chronicles is a failed attempt within the Might & Magic universe.

Maybe, but the storylines in Chronicles are still quite interesting. And the main character is portrayed from 8 different perspectives, going from a fearsome barbarian to an American peacekeeper. That's how much effort they put in! It's a shame that they OVERdid it. But still, all the campaigns are interesting in their own way.