I bought only three brand new cameras in my life: SFX-n, Z-1p and the last one, the K-1.
With the first one it came the "standard" zoom, a Pentax-F 35-70mm. I sold it almost immediately because I was horrified by its plasticky construction. After reading the reviews and checking online the pictures it can take, I regretted my choice... and a few years ago I bought it back
F lenses look and feel quite terrible, but even the cheapest ones are built better than many newer objectives.
For example, late silver FA zooms with plastic bayonet have a VERY poor build. A true pity, cause the optical performance is quite good for the price.
The best Pentax-F I ever tried is the 50mm Macro. Robust innards and great sharpness. Maybe even better than the FA Macro 100mm.
The 85mm Soft Focus is another F lens i treasure.
Some of the zooms aren't exactly the best in their respective range, but I should at least try the 70-210mm on the K-1. I expect a solid performance..