JMT/Rae Lakes Loop: hiking is straightforward and fast, no bushwhacking, no getting lost, easy access to help, good opportunity to meet up with friends who prefer a more guaranteed route; on the flip side, abandoned TP and trash, rangers who hold justifiable suspicion of most backpackers, music on trail, pack trains bringing luxury goods, permit and parking woes
Off-trail or little-used trails: solitude, less regular trail trash but not none, always having a pick of the best sites, get smiles from rangers when they issue your unconventional permit or run into you on trail; but, deeper uncertainty about stream crossings and snow, occasionally losing the trail, no easy access to help, off-trail is both a physical and emotional challenge (eh this is also a pro)
i have no immediate plans to hike the JMT, but i have a feeling i will eventually hike most of it, in the course of other adventures, or maybe tackle it south-to-north in a dry shoulder window for the hell of it, maybe to even link a bunch of non-technical peak bags. it serves its purposes. let the flames draw in most of the moths so the rest of the moths have the night to themselves
