I've just gone through the recent posts.
The feedback given by a significant number of pentaxians falls pretty much in line with my own findings/opinions.
We either influence each other or there is a widespread agreement on which are the most significant MF lenses available for the PK/M42 mount!
Even when it comes to zooms, the chosen ones are most of the times the same ones:
Pentax-A 35-105 and 70-210, plus the Tamron SP model 19AH and 23A.
I guess this thread will stand for long as a valuable source of information to those seeking advice about vintage manual lenses.
Kudos to the OP for opening up such interesting exchange of opinions and experiences.
It is a great addiction to a nice, civilized, generally helpful forum.
I end my post with two lenses that recently found their way up to my personal Olympus (intended as the God's mountain, not the camera maker!) of pre-bayonet era optics:
Sankyo Kohki Komura 2.8/135mm
Tokina-made Soligor C/D P 2/28mm
Both are sharp, have good bokeh, and are not plagued by CA.
Considering the age, and the fact that they beat more recent projects, it's quite an achievement!