It's a toss up between 08 and 09. 08 mainly because it was the year of Samoa Joe and his buildup towards the TNA Championship. It was about time they put the belt on someone that wasnt from WWE/WCW and it was fresh and EXCITING. 09 because the Main Event Mafia was in full swing and it was good to see Sting being properly booked as a heel the way WCW should of done in it 99. Plus it had good matchups and feuds and it was entertaining. It hasnt been that way in quite sometime.
As far as them breaking away when they did, i would say it was a smart decision.