I have owned F, F2, and F3. The F2 is a very strong camera, higher shutter speed, than an F, the F3 is more modern, but the F with a non metered pentaprism, and 50mm 1.8 is just classic. But for the long haul the F2 would be my pick.

Other camers to think about, Spotmatic, Canon F1, and Minolta 201 or 101. I still have the Spotmaitc I bought in College in 1966, it was used at that. Last serviced in 1986, meter is spot on (no pun intended), will work with hearing aid batteries or just about any batttery that will fit. Lens are very good for the day and still hold up to many new lens.