Blm is easy to learn but one of the hardest classes to master. Even a slight mistake will result in a huge dps loss, Stormblood made it even more punishing than before. Blm rotation only looks Easton paper, but we're extremely punished by movement, which requires us to know the fights better than any other class.
Rdm on the other hand is very easy and very forgiving of mistakes.
If you're unsure, why not go to palace of the dead and try them both out? At least you get to see the rotation til 60.