Olympus OM-1 or OM-3. The OM-1 is the more basic, with a simple center weighted averaging meter. The OM-3 has the more sophisticated multi function metering system, with center weighted averaging, single spot meter, multi-spot metering, spot w/hi-lite bias, and spot w/shadow bias. Both are strictly mechanical shutter, with the batteries only powering the meter.
Then if you want some auto exposure, there are the OM-2, and OM-4. The OM-2 offers the same basic metering as the OM-1, with the added feature of aperture priority auto exposure. You set the F-stop, camera sets shutter. The OM-4 is the most advanced, with the same metering as the OM-3, also auto expoure. All four models accept almost all accessories and full line of Zuiko lenses, which IMHO are some of the finest optics in the world. Then there is the size and weight of the OM series, they are compact, light weight, ane the ergonomics of the controls are spot on. These cameras are rugged, and definitly pro quality. But thats just this old mans opinion(and the opinion of just about everybody thats ever handled an OM).
Rick