Of the normals, the 50mm 1.7 has the reputation of an all around sharpest lens. The 43mm at optimum apature is most likely unbeatable. The 50mm macros are the real sleepers. They aren't as popular due to their speed but are most likely the sharpest of all the 50s. As far as which lens is the "sharpest", it is probably one of the longer macros, but the 135mm f1.8 and the various 85mm f1.4 versions have the rep as being Pentax's sharpest lenses. Some members of the PUG did some tests at one time, maybe you can find them doing a google search.

Isaac