Taking the ball in overtime after winning the coin toss against the Chiefs in the 2018/19 AFCCG.
It was a bitter cold day with some wind if I remember correctly. Given the way the overtime rules are structured + the weather + the fact the defense (particularly the secondary) was playing well, Belichick could've decided to kick, hope for defensive stop, and then all the offense would have needed is a FG to win it.
Instead he took the ball and let Brady, Gronk, Edelman (and to a lesser extent, Rex & Sony) carry them home, knowing they needed a touchdown to seal it without the Chiefs seeing the ball. It was the correct decision.
That might be my favorite game-winning drive ever during the Brady-Belichick era in New England. The Seattle Super Bowl had some great drives, and the Atlanta Super Bowl game-winner was a doozy as well (that throw to Amendola, to the right, about 12-15 yards downfield, still absolutely blows my mind)
... BUT! I think that Kansas City drive was in a realm of its own. The weather, the build-up, the way that GW drive was executed, the 3rd down conversions, and especially the fact that it was done on the road, in a hostile environment; that made it special, IMO.
We've been so lucky.