Quote: I am looking for replacement for my well used and worn 16-50mm/f2.8,
[...]
I don’t see too much info about the 16-85mm [...]I wonder why.
ISTM that Pentax has a new 16-50mm on the roadmap. There's (typically) not much detail though, so it could be at least a year or more. I have a Sigma 16-50mm but I'll probably replace it with the newer Pentax version whenever that comes out.
Regarding the 16-85mm: I got one last fall and it's wonderful--fast, sharp, and accurate on my K-3, and great color.
WRT your title question, my normal 'default' lens has always been the DA 18-135mm I got kitted with my K-30 years ago. The camera is gone, but the lens lives on: it's capable and flexible, if not perhaps quite the IQ of the 16-85mm, at least with my copies. But I left it home on a recent trip and took the 16-85 instead. I didn't regret it for a minute.
traveler