I would have to say our 2012 robot, even though competitively we could have done better, we really came together as a team that year.
It was the first year we used vision. We solved the pose of the robot, and I got to go to the international science fair (ISWEEEP) and present the vision program to a bunch of professional engineers for a week, placing 3rd in the end.
We made half court shots. I haven't seen another robot from that year do such, though I haven't really looked.
video:
http://youtu.be/vzemnptiebk?t=3m2s
It wasn't so much our success that year, but that it paved our way to success for the following year.