Usually L lenses are exotic for some reason due to large apertures or something of that sort... there are non-L macro lenses from Canon that are probably sharper than many of their L lenses, I believe one was the 60mm macro, and there were some in the 100 to 150mm range as well that are quite good.
L doesn't necessarily designate the highest optical quality, or you could make a cheap 85mm f5.6 and call it an L lens. It might not be the most useful lens ever built, but it could be very, very sharp... there are non-L lenses that match L lenses optically, the difference is in things like speed and versatility.