With so many different manufacturers' systems from which to choose, it's impossible to be dogmatic. But I have to say with my Contax Zeiss gear, it was always a tussle between the 50 1.4 or 55 1.2 as the standard, and then either the 35 1.4 or the 28 f2 for wide-angle. If I would be shooting in low light or need very high shutter speeds, it was often the Planar 55 1.2 and the Distagon 35 1.4 BUT if you wanted pin-sharp edge-to-edge and a close focus capability (don't you just love those floating elements!) the Zeiss 28 f2 'Hollywood' lens could not be beaten - until the 21mm appeared and I've never shot with anything as sharp since. And when speed is not an issue, Yashica provides a stunning alternative in their legendary 24 2.8ML and 55 2.8 Macro ML lenses and will cost less than 1/6th the cost of the 21mm. The only problem with these 2 lenses is that over the last 6 months, canny Canon EOS users have started pushing their prices up...