Leica R8 with the 80-200 would be my choice. Film? Not so bothered. Astia? Or if I was concerned about back/neck/arm ache from the 8/80-200 combo, a 400 B&W, probably Bergger, to reduce the risk of camera shake and medical bills.
That makes me one of the few (or only person) with a zoom, rather than a prime lens, to answer. Is a prime really the best choice for a single lens choice? A
quality zoom will spank most primes into the middle of next week. It also increases my creativity (much needed) and reduces walking. What's the disadvantage? Short of enlarging a snap to 48-sheet poster billboard size, none I can think of. Especially at the 80 end of the lens, I'm not at all sure I could tell the difference holding a print between a Leica 80 zoom and a quality 90 prime with the same crop. Yes, Leica zooms are heavy and eye-wateringly expensive when new, but it is a tool for seeing and if I could only choose one rig, a flexible tool for seeing would be my choice. Everytime.
I'm now going to hide form all the prime users' replies.