I just don't think any season will surpass season 2 for me. The contestants were regular people, the production had no bandzilla.All the worn out songs idol does were new then and I really enjoyed the group numbers and medleys. The voices blended well.
The show was just beginning to act likea juggernaut. There were actual water-cooler discussions in the workplace. Then you had the whole Ruben vs. Clay drama, and the voting scandal. It really got me back into going to live concerts (Idol and others). It was so much fun meeting Idols and fans and holding up signs. Made a lot of friends and acquaintances through that season.
Season 4 was also very good - Carrie vs. Bo. Great voices. And I liked the David Cook Season 7 a lot. He was such an unexpected winner. S5 gets honorable mention because Elliott didn't win.