I personally went with Tektro R556 myself, ride with them everyday. No problem so far, didn't change the pads out either. Dual pivot brakes, once set up properly they have lots of stopping power.
Also, depending on your bike frame design, you can get the Tektro R556 in either a recessed or nutted style set up now. Before this wasn't the case, I had to buy a set of R556 recessed and a cheaper set of Tektro brakes that still used nuts and swap out the mounting bolts myself. That was such a pain in the butt.
Look at this BF post.
http://www.bikeforums.net/showthread...00c-conversion