I own and still use a Rollei 35 with the Tessar lens. Very nice, sharp lens. Mine is Singapore made. From what I can tell there is absolutely no build or quality issue between the German and Singapore models, just a premium for collectors for German-made.

Per http://johnlind.tripod.com/rollei/rolleitext.html , the Sonnar lens is multi-coated v. single-coated for Tessar, Triotar and S-Xenar models; and it is acknowledged as the superior lens. The Triotar is the only one that might be avoided.