What's the difference in using 楽 and まし. For example: 死んだほうがましだ against 死んだほうが楽だ. They both mean "It is easier to die (than to do something else)"
They are semantically different words. 楽 means easy (antonym for tough/tiresome/hard) whereas まし is nuanced better, or "not satisfactory but at least better than something even worse" (See: What's the meaning and usage of ~マシだ).
死んだほうが楽だ and 死んだほうがましだ does not sound that different simply because 死ぬ is a thing that is normally both tough and bad. But tough and bad is not always the same. For example, imagine you are a traveler and decided to take a long, steep but safe mountain road, avoiding a short but bandit-appearing road. In this case, the mountain path is tougher but better. So you would say こちらの山道の方がマシだ, but not こちらの山道の方が楽だ.