Originally posted by Jonathan Mac The K series are just the right size for m hands, which is the main reason I like them. The Minolta SRT series are very similar (and also very nice indeed).
Yes classics other than the Pentax mentioned in earlier posts include the Minolta SRT series and for more automation the X700. Nikon FM2, FM2n, FM3a, or my favorite, the F3HP. I own a Nikon N2000 which has survived years of insults because it wasn't a pro model, but works great. The Nikon FM10 (or it's twin the Vivitar V3800n) are the more plastic and modern versions of the K1000 as is the ProMaster 2500PK that accepts K mount lenses. The Canon AE-1 became the defacto camera in the late 70's after the K1000, but the only MF Canon I would consider is the A1.
Autofocus has come a long way and if you're used to AF with a DSLR, you'll find AF with most FSLR painfully slow and inaccurate, and manually focusing those lenses and with those camera finders, less than ideal. But if you wanted to go AF with a non-Pentax, I'd suggest either the Nikon F100 or if you wanted weather-sealing, go to the bank and finance a Nikon F6.
Value-wise? Stay with Pentax! Although new lenses aren't backward compatible with manual exposure only film cameras, at least anything you get for the K1000 will work on a new Pentax DSLR.