Stewart is a really good comedian but also a really big hypocrite when he decided to start making political commentary and then fall back to "hey I'm just a comedian/entertainer" when he started getting called out for it. I have no intention of ever watching the Late Show with Colbert for that reason alone. Colbert is 10x worse and half as funny as Stewart.
The only time I've ever watched Clarkson was when he tried driving the three wheel car that kept rolling over.