Originally posted by brightseal Why do you all like the M's ?
I'm gonna horn in with my own answer...
I started my journey into manual lens land with a Sony mirrorless and chose Pentax M lenses due to cost, size, and excellent image quality. While I have almost all of them and don't plan a divestiture at this time, if I were starting over with a K-1 (+/- mII), I'd choose either K-series lenses or A-series. Of the As, I'd choose those that are clones of K glass (ie, 15f3.5, 50f1.2, 300f4) and any * lens. This selection is indeed larger and heavier, sometimes by a lot, compared to the Ms, but IQ and balance on the FF DSLR is often better.
The only exception in the M- series I can think of that is truly unique is the M20f4, which is so tiny yet excellent I'll never give it up. (cue Rick Astley)