I haven't play all the FF (only VI, VII, X, X-2 and XV) but this series is kind of "magic" for me and I can't resist to be hype for each new FF.
I was really hyped for XV (I mean Versus XIII), got a bit disappointed but enjoy it quite a bit in the end (but yes the story is a bit fuck up). I even think doing another play through this year to see the changes they made (and I'll probably enjoy a bit more because now I know what to expect).
Final Fantasy XV improves a lot thanks to the many contents of the many free updates of the game, and also thanks to the addition of all the DLC.
The Royal Edition and the Windows Edition are the most complete versions of the game, with the only difference that I don't understand Episode Ardyn which must be purchased separately. But once you have tasted the whole Final Fantasy XV narrative universe, you will fall in love with it.
I heard that quite often. It got me really hype to try it. Always wanted to be a MMO fan but those I have try could not keep me interested long enough.
Does it really feel like a "single player" adventure (MMO combat aside)
Final Fantasy XIV is an MMO and an excellent Final Fantasy. But it also requires a lot of patience, above all also because of the many very banal fetch quests that interlude the events of the very multifaceted and very rich and complex history.
For the gameplay you can play safely even alone, but you will have much more difficulty finding groups that help you in the dungeons and who also have the patience you need to complete them.
I, for example, the first time I finished Final Fantasy XIV A Realm Reborn, in the last dungeon, I was so far behind in the dungeon that the whole group already knew it by heart, and I not only could not do anything but I couldn't even see or fight the final Boss for this.
Because they had already gone all their way, and they had already beaten all the stages of the final Boss
(then they corrected by adding a preparation barrier, but before it was not there and I had this experience)