I use Gatorskins and have very good results from them. The sidewalls are super strong and flat protection on the tread bit is good too. I tried the Marathon Plus but got a load of flats so stopped using them (average one flat every 13 commutes) whereas with the Conti Gatorskins, flats average one for every 70+ commutes. I use the 700 x 25 size.

Rick / OCRR