Sterling,
Seriously, the 'mother of all shooters' is a VOPO. These postwar East-German police guns were reworked just after the war and have no serious collecting value at the moment. I just bought one for about 250EUR, with 1936 Mauser frame, DWM toggle and postwar barrel. These thingies shoot like razor blades.
The next best are the postwar reworks from former Russian and Eastern European supplies. These were reworked on later dates and most have new barrels added and are reblued. These are priced in the 600 - 900 EUR ranges. Rework quality is better than the VOPO, shooting quality usually isn't, they just 'look' better
After that I would shoot an original non-collector's gun (with mismatched parts, so you don't destroy too much history and finances when things go wrong).
4th place are the new US-made stainless guns. Less classic but still fun.
Definite no-no's are collector grade guns and postwar Mauser Parabellums (unless they fit into category 3). I would also feel guilty about shooting Thor's masterpieces, but that's just personal <img border="0" title="" alt="[Wink]" src="wink.gif" />