I reckon the Scotch ones are the best.
I was lucky enough to be able to spend some time with Scott Hanselman over the DevDays conferences. Scott is one of these folks who have technology running through their veins. It was great to see his eyes light up whenever he was showing off a cool new program or discussing the future of computing. However, I did actually have a gadget that managed to impress him, which was nice.
At one point during our chat I produced the micro-fibre cloth that I carry round to make my Windows Phone shiny bright before each demo. This went down very well, and was promptly put to work shining up all the devices we used for the keynote.
If you want to get rid of all the pesky fingerprints that these devices seem to accumulate then I recommend that you get one or two. You can get really good ones from the Pound Shops in the UK and places like Tesco also do multi-packs at a good price. But if you are properly rich you can get the original Scotch versions above.