Ffxi had merits/job points and subjob system which allowed huge flexibility and unique gameplay tactics....unfortunately, this led to huge problems with job balance for the last 12 years and had things like white mages tanking the hardest bosses by exploiting ninja spells or bard songs, etc. ffxiv uses a trinity system where there's verrrrrrrry little flexibility but balance is so much better because of it. If you want customization and flexibility, prepare to sacrifice balance and harmony.