For me, it would have to be 2005.
I started playing Tiger back in 03' which was the first year they incorporated the real-time analog swing into the game and I was almost immediately hooked. I remember getting so good I could whip all my buddies asses with ease and salivated at the prospect of PS2's online play for the following year of the franchise as I was sure that I would be an instant ass-kicker....that was until I found out about the concept of auto-turbo controllers being allowed for online play. =(
But eventually, I gave in and IN 2004 I purchased an auto-turbo controller and playing online w/ the headset microphone communication made the experience AWESOME!!
As fun as 2003 and 2004 were, I have to go with 2005 as the absolute pinnacle year of the Tiger Woods franchise due to the excellent course designs as well as the handy new feature of ball-in-stance character positioning.
In my opinion, EVERY consecutive year of the following games in the franchise after 2005 have been worse & worse.
I can understand that the game was getting too easy to play, but starting in 2006 EA's attempts to make the game more challenging went from bad to worse.
I feel all they have done every year since 2006 is made the game un-fun & undesirable to play.
I haven't bought a new version of Tiger Woods for the last couple of years now for this reason, as well as any other Electronic Arts titles period because it has become quite clear to me that EA Sports doesn't give a damn about any other sports games they publish besides "Madden" and that's it.