I do a fair bit of day hiking, but not the longer sort of trip you're planning (at least not yet - I harbor delusions, err, I mean dreams, of hiking the length of Hadrian's Wall one of these years). That said, I will still offer an opinion. First and foremost, you want a camera with which you are thoroughly familiar and comfortable. Nobody wants to be messing with equipment on a trip, hiking or otherwise - it's an unwelcome distraction. Size and weight matter too, of course, but an extra pound or two is not going to make or break you. Ideally, you find something that fits all of these, but if not, go with the one you're comfortable with.
As a minimalist travel example, I shot Berlin last year with just a Leica IIIc and a collapsible Elmar 50/3.5. Small, light, fits in a pocket, and I can operate it in my sleep.