Belichick without question. People say you can't win a SB without superior talent... how about the Pats circa '01/'02? That team had nothing, absolutely nothing, save for a Ty Law in his prime (keeping in mind, Tom Brady wasn't much more than a game manager back then). Best coaching job in history...
And yeah, BB's won a lot more with than without Brady, but Brady without Belichick is likely languishing at the bottom of a depth chart somewhere below some loser like Aaron Brooks, getting his 100th chance at being a starting QB... Brady's a good QB that's the product of a great system.
One more thing; why does everyone assume Belichick is some huge #######? You never hear him criticize, or whine, or show arrogance... he may be a little wooden, but is that really worthy of the hate he receives? People love Brett Favre with a passion, but he was a jackass for two years, holding GB hostage with his will I/won't I retire BS ("What are they gonna do, cut me?") There was a piece on espn page 2 about Belichick the other day, one portion described how he pulled over at the scene of a car accident, took charge, and likely saved a guy's life. He's a private, introverted guy who obviously lacks social skills, how does that make him evil?