I really debated over which way to go when I boosted my IS300. So, I'm going to to say that in my opinion, turbo blows away superchargers. With a supercharger comes belts, and with belts comes problems. Whatever size pulley you use is what determines your psi, and it's always on. A supercharger does have engine drag, although not as much as before. So even when your not using it your motor is lugging it around. they have put some tech into developing some better designs. There are better superchargers out now like the Kenny Bell supercharger system I put in my 03 Explorer.
But, In the last few years there have been some big dollar car mfgrs with rejuvinated interests in the turbo because of what it offers deisel motors as well. Over the last 10 years, there have been alot of amazing developments in turbo applications. Audi is winning Lemans one event after another with thier new turbo deisel rocket, Ford just came out with a V6 turbo that offers more torque and hp then thier new 5.0 liter V8 and is the "upgrade" from the V8, meaning it costs more? It's selling. My turbo set up has a digital boost controller with 2 settings. With a push of a button I can go from 14 psi (about 380 rear wheel hp) to 24 psi ( about 520 rear wheel hp.) and still get 28 mpg around town. The turbo only goes into boost when I decide I want to. Most of the time I drive around in vacuum mode and stealth along though. I hid the intercooler behind the stock grill and I use an internal blow off valve to recycle boosted air. You'd almost never know it was a turbo IS. So because the turbo is getting alot of technology, has more versatility, and is being used more and more industry wide meaning more platform support , and also the turbo is much more efficient than a supercharger, and can make way more power than a supercharger can, I say turbo is better........