Pentax is a bit of a paradox to me. They have excellent lenses, which scream "high quality!" inside out, are optically and mechanically good and even their innards leave you with certain sense of satisfaction, if you disassemble them to service. As for the bodies, almost each one of them leaves you wishing for something more. Here are some that I had and got rid of, shaking my head with displease:
K2 - No doubt it's one of the best (if not the best) model of early seventies, has everything a user might want/need - DOF lever, Aperture priority, exposure compensation. The only downside is the absence of AE Lock, which was addressed in later DMD model. And of course the size.
KX - Still a bit item. I know that size is subjective, but I'd much rather have compact gear.
ME Super - this one was closest to my personal preference. Unfortunately I'm not a fan of button layout, preferring old fashioned dials and knobs, so it never stuck with me.
MX - price point is what I dislike and this might sound like a rant, but "fully mechanical" and "infinitely repairable" are not the arguments that would justify the price.
Whole P3/P3n/P3t series - no exposure compensation and no manual ISO input. I know it's an entry lever camera, but still.
Program A/Super A - Again, not a fan of buttons and these two are on the "taller" side.
So in the end, I stuck with Ricoh (not a Pentax) XR7 which has aperture priority, DOF lever, exposure compensation, AE lock and multiple exposure lever. At a price of it having plastic covers on top of metal body. Looks cheap, feels cheap, but works like a charm.
In the end, probably the best K-mount camera with Pentax engraved on it is LX. And while it doesn't have AE Lock either (Pentax, what were you thinking?!), it has just about everything one might want from camera. If only it wasn't so expensive. Although unlike with MX, this time price seems justified.