You mean I have to choose?
with rangefinders: Leica M3, no brainer.
SLR, I would have to say the Nikon FM.
I own a lot of pre Ai bodies (F, Photomic Tn, Nikkormat, and F2) and two AE bodies F3hp and FE. The FM is simple, reliable, compact and reliable, plus if the batteries die, it's not a paperweight.