Disclaimer ARR sucks and is gruelling, but the backstory it provides is important for later content. Heavensward (next expansion after ARR) is really good. It's better organised and directed. Hits you in the feelz department. Stormblood is my personal favourite (people usually either prefer HW or SB). SB has my favourite storyline, environments, dungeons, raids (minus Omega), and trials so far. I can't really specify without fearing of spoiling...


Another good reason to FFXIV (youtube, no spoilers)