It depends on what you want in terms of automation and newer is not necessarily better. With the exception of the flagship models, build quality industry-wide declined from the late 1980s on. See below for my "no reservation" suggestions. All on the list are either manual exposure or auto exposure with option for full manual.
Pentax KX (M exposure)
Pentax KM (M exposure)
Pentax ME Super (Av and M exposure)
Pentax MX ($$) (M exposure)
Pentax Program A/Program Plus (P, Av, and M exposure)
Pentax Super A/Super Program (P, Av, Tv, and M exposure)
Pentax P5/P50 (P, Av, Tv, and M exposure)
Pentax P3n/P30n (P, Av, and M exposure)
Pentax P3t/P30t (P, Av, and M exposure) (if you don't mind plastic film door)
(Note: P-series bodies do not allow manual setting of ASA/ISO film speed and require DX-encoded film canisters, but otherwise are very cool cameras in my book.)
Ricoh XR-1/XR-1s (M exposure)
Ricoh XR2/XR-2s (Av and M exposure)
Ricoh XR7 (Av and M exposure)
(Note: Ricoh made a plethora of K-mount camera models, most of which differed only slightly in features and build. I have personal experience with the five models above (all from the late 1970s/early 1980s) and can vouch for their build and performance.)
I have no experience with Pentax AF film bodies and can't make any recommendations from those lines.
As noted above, most film cameras will require seal replacement at minimum* and many would benefit from a full CLA. Jon Goodman's seal kits are grade-A, are camera-specific, have detailed instructions, and very inexpensive ($10 USD, shipping included). There are other kits, but his stand out. I have bought multiple kits from Jon and none has disappointed. In addition, he is a genuinely nice guy and a pleasure to deal with. Jon deals exclusively by e-mail at present, but is usually very quick to respond to inquiries:
jgood21967@aol.com
KEH is a good resource for purchase and not overly expensive. They test and warranty what they sell and cameras have often (usually?) been serviced prior to sale.