It really comes down to how much work you are willing to put into your forced induction setup to make power. Both a supercharger and a turbo charger will make significant amounts of power but both have their advantages and disadvantages.
In my experience turbos have the ability to make more power then superchargers, especially in dual turbo setups, however it is not just as simple as bolting a turbo and new exhaust manifold to get that power. In order to really take advantage of a turbo you also have to do some significant work on the engine including changing the camshaft and engine timing, compression ratios, and head designs to name a few. By no means an easy weekend project but the results can be phenomenal.
Superchargers on the other hand I think provide the best bang for the buck for getting more power out of an engine, especially a larger engine where the torque loss required to drive the SC is only a small percentage of the starting torque. But more importantly anyone can take a supercharger and bolt it to the intake manifold and realize significant power gains without any other mechanical changes to the motor, a true weekend project. Sure a supercharged engine will benefit from all the additional changes really necessary for a turbo, but you will see far better power improvements from a stock motor with a supercharger then you will with a turbo.
Bottom line is dollar for dollar my money is on a supercharger for forced induction. Plus that whine that comes from the sc is just a bitchin sound to hear going down the road...
Of course that's just my opinion, I could be wrong.