The problem with handpicked brackets is just that it's extremely tough to balance them out properly. You don't know if there will be a first round upset, so you can't realistically plan to set up big matches in later rounds, but when you stack the first round you end up with the middle rounds being terrible. I seem to remember that happening once, I think it was the villains contest, where there was a match like Unicron/Galactus in the first round that was somewhat close and then the winner basically scored a shut out from there until the finals because the only opposing votes were just fanboy rage. Setting up a "big" match to be the first match of the contest is a good idea to get things started on a good foot, and maybe put another one somewhere else in the first round to keep momentum going, but otherwise it's better to do it with a heavy random element. It leads to more unpredictability AND means that if things get dull you can just blame luck instead of people criticizing your decisions :)
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We clasped our hands, our hands in praise of a conquerors right to tyranny