The quarterbacks that I trust the most with the game on the line are Colin Kaepernick and Sam Bradford.
They are both cool under pressure and are able to direct the offense like a coach. I was able to watch a game last year in St. Louis that had both quarterbacks and it was a close game. Kaepernick is very athletic and able to run away from the rushing blitz with amazing speed. You can see that he is a true athlete and is similar to having an extra running back. He is also able to run around to avoid getting sacked by the defensive lineman.
Sam is a traditional passing quarterback. He sits in the pocket and can hit his receivers with great accuracy. He constantly has his head on a swivel and is able to check off on multiple receivers to see if they are open. Sam does not seem to get nervous when he is back there ready to pass, even when the game is close and they have to score to win.