I've hiked with medium and large format film cameras, but my favorite is the Rollei 35, from the 1970's. Small, sturdy, and has an excellent Zeiss lens. I have better cameras but I seem to get my best shots with the Rollei. It's a quirky camera, but has a cult-like following and you can expect to pay $200-400 for the most preferred models (35S and SE) that have the Sonnar lens, although he Tessar lens on the 35 model is excellent too.
I did the 100 mile wilderness on the AT a few years ago with a Contax G and three lenses, and had a blast.
I shoot only B&W and develop and print in my home darkroom.
I've tried digital, and went back to film.