It really depends on what you want. They're very different games. They both have great exploration and questing, albeit FF14 has always been rather slow and tedious. If you prefer a specific lore, such as being a fan of final fantasy, then you'll enjoy it more, but if you don't care that much about either or don't know much about them at all, then ESO is superior in this aspect with engaging and meaningful quests that are fully voiced, along with more exploration.

When comparing group content, then ESO falls a bit flat in comparison, so if you want group PvE, this is where FF14 excels. ESO has superior PvP, but lackluster end-game PvE. The trial system has always been either extremely easy or rather chaotic, it's a different type of difficulty compared to FF14 end-game.

When comparing the combat system, ESO is more spam based and is very dependent upon animation canceling. While FF14 is memorizing a ton of skills and the order to cast them in for optimal damage while being slower paced.

Other than this, the gathering/crafting system in FF14 is far superior.

All of this will stay true regardless of expansion, unless there are some major overhauls I'm not aware of.