Personally, it would have to be the finals at Philly, 2008.
You had the alliance of 103/272/834 (three high ranked, high powered shooters), VS the alliance of 365/341/84 (solid alliance, not as fast at hurdling).
No one thought that 103 would lose, at all. They had outscored everyone else by wide margins the whole weekend. Sitting in the stands, and watching the finals matches was one of the most exhilarating experiences ever, for me.
http://www.thebluealliance.com/event/2008pa