tough call, usually most people ask about 05, which was probably the worst game in history. in 05 you couldnt even establish a forcheck, you came in and either shot or did a one timer, then they had a rush, then you had a rush, biggest wast of 50 bucks ever.
on the topic though, 04 was a sick game for passing and plays cause it took skill to do the different passes, but o6 is more fun due to the fact you can set up real plays and establish control in the O-zone.