If you consider Nikon check the FE/FE2 as well.
I like it better than the FM, very rugged (mine is 25+ yr old)
For an excellent Nikon classic compendium check:
Has comprehensive info in each model and even instruction manuals.
As per Pentax, I consider those bodies top notch, and the Takumar glass is awesome!
I own a couple of Spotmatics (screw mount) and love them.