Lets try not to turn this thread into a Supercharger vs Turbo thread.
But I just have to add my two cents
Ford and Chevy have far more turbo charged vehicles on the road then supercharged ones so that should answer your question as what is better. I'm guessing its a lot cheaper for companies bolt a TVS supercharger on top of a performance V8's vs going the turbo route which is more costly and is more prone to warranty work (think Audi S4's). But this past year quite a few supercharged vehicles got turbos and my main guess is due to increased fuel economy and power/ efficiency (AMG and BMW have more then a few new turbo engines this past year) and the Cobalt SS/TC is far better then the SS/SC.