Olympus OM-1 is one of the best cameras. Pretty lightweight. Lenses are very good (and compact) too.
Pentax MX comes pretty close to that, my only complaint is that shutter speed dial is somewhat uncomfortable to use.
Nikon FM is great too, no doubt about it. Far more ergonomic than other two. Its action is far more pleasant. Butter-smooth advance lever, shutter dial with firm clicks which can be operated with just one finger. And do I even have to point out that Nikon glass beats the other two?
Oopsie, there are no semi-automatic or automatic cameras on my list

That's because there was no clear definition of what's "best", so I listed those that are best in my personal opinion. To me, "best" means lightweight and with good ergonomics. But above all else, given the situation that almost no new cameras are being made and spare parts will start to become scarce, an important factor is that the camera must be easily repairable/serviceable on my own.