"Play what you want!"

[Felis]

Op: "Hey I'm trying to decide on the one meaningful decision we're allowed to make in the game andI'd like some insight."

The one meaningful decision we're allowed to make in the game is the appearance and the name of the character. Classes and jobs are changeable with just equipping another weapon or tool after they finished the lv 10 class quest of the starting class.
"Play what you want " mean "test out some classes and see what make more fun for you"