Nikon FM2 (or FM) might be a good choice. If you are willing to spare the bucks,you can consider the F3 too.
offhand:
FM2 has the higher flash sync speed (1/250), F3 has TTL, slower (1/90 or was it 1/80?) but F3 has its own unique flash shoe vs the usual Nikon flash.
FM2 is fully manual, F3 still has aperture auto feature.
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In terms of manual SLRs, the main thing is the intuitiveness of use. Your left hand sets the aperture while holding/supporting/focusing the lens. The right hand sets the speed while holding the grip of the body.
And of course, when loading the film, remember to set the ISO correctly (or in the lingo of old timers - the ASA).
Exposure wise, you have 2 look at a couple of LEDs in the viewfinder, the selected speed LED lights up in the viewfinder etc.
2 other considerations -
- easy availability of getting lens (used/new market)
- option of getting a SLR with both manual and auto capability. By the time you are done learning, you may be yearning for auto exposure, auto focus etc and then what, the favourite exhortation of "BUY, BUY, BUY"