My first choice is Beatty from 2002, but enough people have commented on that one, so I'll choose some other robots, too.
I think WildStang from last year may have been the best robot of all time, certainly of last year. I know 25 went 36-0, but you know who gave 25 its first
defeat? WildStang. This robot could do everything better than any other robot. It had arguably the best autonomous mode last year. It could pick up off the ground like a champ. It could get on the ramp (and ramp shoot!). It could play defense. But the most impressive feature was the turret. The robot could be moving horizontally across the field and and the turret would stay constantly pointed at the goal, balls always pouring in. 25 may have beaten 111 in the Newton Finals last year, but WildStang put up an amazing fight.