Upload & Sell: On
...is there a consensus on *the* Leica-R lenses worth having in one's collection?
"Consensus" might be a bit strong. The top R lenses are good enough that whether they are better than other top lenses is mostly a matter of taste. Most R lenses have been surpassed from a technical standpoint, though their handling, durability, and relatively low cost make them desirable for what they do offer. Personally, the stand-out feature of most of these lenses is that they address my pet peeve, longitudinal CA.
A typical can't-really-argue-against-but-for-cost kit might consist of the latest 19/2.8, 28/2.8, 50/1.4, 90/2 or 100/2.8, and 180/2.8. Anything APO, as those last three are, plus a few more telephotos (which aren't my area of expertise).
A set of lenses that might be better for storytelling than pristine documentary would be the earlier versions of all those lenses. Additionally, the 35/2.8, 50/2, 60/2.8, and 90/2.8 lenses all offer good value, at least as far as Leica goes. This isn't comprehensive, just from the top of my head.