Hunting compass or smartphone with a map - which is more reliable in the forest?

A compass is more reliable long-term because the battery doesn't die and it won't break from moisture, while a smartphone in the forest can run out of power at the worst possible time. But ideally you'd have both: a smartphone with an offline map loaded is great for navigation, and a compass is a backup if your phone dies or you lose signal. I personally take both plus a paper map in a waterproof bag - that way I feel more confident in the taiga.