I think none of these. Like with roads it should be more about importance, function or usage (we have already that distinction for footway vs bridleway vs cycleway).
For example, some paths are specialized for mountaineering, requiring equipment and permits. Others are official hiking trails, maintained and marked by national parks or local hiking clubs.
Then there are informal or unofficial trails, which could be anything and are entirely at your own risk. This could address the safety aspect, with a different top-level tag rendering users: “You’re outside an official, maintained area—proceed at your own risk.”