I would think winning close games would be better for a team's psyche down the line. If the game is close at the end, the Patriots are very confident that they'll do what it takes to win.
Thirty years from now, they wont be examining how much they won by, they'll just be marveling at how often they won.
Does it hurt any less if the Bills only get beat by 1 point as opposed to 14+? Are you into moral victories?