Just got a Leica IIIf. Please educate me on good lenses.

[BillBingham2]

......the Leica 90mm f4 Elmar is inexpensive and EXTREMELY sharp.

Mine was amazing. IT lived on my M4-P for many years. Should never had sold it. Small, sharp, one fine little lens.

Larger but equally as sharp (perhaps more) is the Nikkor 85/2.