[Lil' Lavery]

Aim High, but it was basically a tie with FIRST Frenzy. Both of those games were quick paced, exceptionally exciting, and had lots of action. Tough defense, balls flying through the air, scrambles for "king of the hill points" (in the form of the bar in 2004 and the ramp this year), etc.
I liked the wide open field design in 2006 more though, and that's what gave it a slight edge. More room to maneuver, fewer bottlenecks, etc.

I'm surprised so many people have said 2003, Stack Attack. From the general consensus of other areas in the forums it seemed like nobody liked that game. Too much defense, and a lack of reliable and quick stackers seemed to plague its public perception.

I don't really like the 2001 or 2002 games. 2001 was confusing for spectators, hard to score quickly, and lacked an opponent (4 v 0, eww). Plus the elimination ranking system was actually biased to the #1 seed that year. It was 5 teams per alliance, with 2 teams automatically paired (1&5, 2&6, 3&7, 4&8), with the 1st alliance getting the first pick in each round of the selection "draft". 2002 was a bit chaotic for my taste. The zones could get confusing, especially if you were not familiar with the game.

2005 had it's charm. It has the most obvious strategy of any game (but many games have vast layers of underlying strategy that many people do not recognize), but tended to be not as exciting as other games. Defense was very limited, and there was no autonomous interaction. I really liked the move to 3 v 3 instead of 2 v 2 though.

I'm not really familiar with any game before 2000, and my interaction with the 2000 game was limited, although from the bits I can remember, it was exciting.