The old school forumites are gonna be spamming the thread with "2006 BY FAR, DEAL DIED WITH LAURA'S JACKPOT WIN! LONG LIVE KES!!!"
While I understand that opinion, 2006 wasn't quite peak Deal for me. My favorite years were 2007, 2009, 2011 and 2014, the last one mainly being because I was active on the forum throughout that year.
I think I'm gonna go with 2007, though. Laura's jackpot won started off the year and the aftermath of of it produced insane gambles galore to an extent that wasn't seen before and since then. Then that eventually stopped at the end of May (1k Lynn's game being a turning point for the gambling tendencies and Sarah's game that month ending the trend of insanely generous offers from early 2007) but there was still plenty of characters and players that were willing to play the game aggressively afterwards.