None. They all can't predict better than the average college basketball fan. The NCAA Tournament is such a crap shoot.
One year I filled out a bracket just using Kenpom's ratings. I picked every game by who had a higher Kenpom ranking. It was a terrible bracket. Worst I've ever done.
I think you just need to make educated guesses going with the higher seeds most of the time. Pick 1 team, a very high seeded one, you think will win it all and ride that team to the championship.
Something tells me you used Kenpom incorrectly. It might not be the end all, be all, but for the sake of discussion, just because one team is ranked ahead of another on kenpom doesn't automatically mean they are favored to win the game.
And while you're correct it's a crapshoot (again, for the sake of discussion, Craps has the best odds of winning of any game in the casino albeit you are still destined to lose), there's some level of non-crapshoot. Seeds 1 thru 4 have advanced at least 75% of the time out of the first round, and at least 68% of the time from the second round. 1 Seeds have made it to the sweet 16 86% of the time, which means you could reasonably place a 4 leg parlay on all 4 one-seeds to make the sweet 16 and feel pretty good about the odds of that happening versus the odds of the parlay (+308 as of this afternoon). Your last statement on that account is perfect, especially for standard bracket pools - the odds of you winning your pool and not having the national champion (or at a minimum the two teams in the championship) are really small.
Anddd I've gone way overboard with this rant.