All the 6-element lenses from the major manufacturers are pretty good--Rodenstock Rodagon, Schneider Componon-S, and most of the EL Nikkors (though I had the 4-element 75mm EL Nikkor for a while, and it was a decent lens).

If you have the budget for an Apo-Rodagon or Apo-Componon, these are really outstanding, and are pretty good deals on the used market. I use 50mm and 90mm Apo-Rodagons and a 150mm Apo-Componon.