Without looking into finances and product release stats:
I'd say Succession Wars, IlClan have been the most successful, followed by Clan Invasion and Civil war, there's a lot of people who got into the Clans and a lot of Feddies to support the products.
Worst Jihad and Dark ages, I think a lot of people had presumed BT was dead and floated away and missed the Jihad and a few people didn't like the Dark ages, but that's just BT, for the Clix players DA would be the most successful.