I know that all things aren't equal, but if they were, I think the advantage goes to Belichick. I think he has more variables to play with (more levers to pull), and he has more opportunities to effect change. I know Brady is lauded for his leadership buthe's still one guy and if (or when, if you're inclined to that world view) he and Ariens perhaps do not see eye-to-eye on something, it's potentially a problem.
If Belichick and Stidham don't see eye-to-eye, well, good luck in Cincinnati, Jarrett. I hear they have good chili out there.