Others may not agree with me, but this is my opinion:
The 2007-08 Celtics season was the greatest single season any NBA fanbase has ever had. When you look at where we were at the end of the 07 season, and where we wound up just a year later, nothing like it has ever happened before or since.
The greatest franchise in league history, at perhaps its lowest point, somehow pulls off a series of major gambles that ALL WORKED, and turns the second-worst team in the league with a #5 pick into the greatest turnaround in league history, a redemption of the careers of the Big 3, glimpses of a budding star (Rondo) and a longtime project finally coming into his own (Perk), one of the greatest Game 7 duels of all time where our captain outplays one of the two best players in the league, and tops it all off with a historic beatdown over a (then) ridiculously overhyped Lakers team and a Finals MVP for our long-maligned superstar, who only had to outduel the OTHER best player in the league to do it.
If it had been the plot of a movie we'd've mocked it as ridiculous. Celtics 131, Lakers 92, Paul Pierce named Finals MVP is the sort of scenario I'd've doodled in my notebook in 3rd grade. And it happened.
That season was like a giant Christmas present we got to unwrap over the course of 11 months. I wouldn't trade it for anything save the survival of the franchise itself.