My opinion could very well be because of the amount of time/money I put in or even rose-colored glasses but I personally find FFXI the more complete MMO out there to my tastes. Also, I feel it is one of the last remaining "old-school" Final Fantasy's that generally stayed true to form (minus any spin-offs/remakes/remasters and I haven't played XVI yet).

I find the story for most of the game very well written but with expected retcons (pretty minimum actually although Rhapsodies' story line border-lined full on retcon) after so many years and likely different scenario writers. I also find that the quests, although vague on what to do or where to go at times, actually add to the lore of the game for the most part. Some even connecting to the overall mission story of an expansion or two (but not necessary to complete said mission/expansion).

Compared to XIV, if going to the other MMO within the same name, I feel the jobs in the game have a fairly defined identity where, for better or worse, hopefully always stay that way.

I also feel that despite various limitations the game might have, I believe it has aged extremely well with it's graphics, battle system, and soundtracks. Again, this is my opinion as I don't care about today's AAA graphics and while I like it's simplicity, I find battle structures similar to XIV, Rfit, etc. doesn't line up with my own personal taste.

I like that you effectively keep all your spells/abilities and are mostly not removed/replaced after every update/patch even when expansions were released.

I also like that when I play the game, I find very few things that "need" to be adjusted (quite a few structural/logistical wants though) and I can for the most part, play the game in full as it is without major reconstruction or any mods.

The catch is of course, most things in the game pretty much require a wikipedia to proceed as mission/quest markers pretty much do not exist and the dialog for most things were written with old school MMO in mind.

All that said, I likely play the game with a different mindset than others but the game has pretty much kept my subscription for probably 20 years now where I had very few "downtimes" where I stayed unsubscribed.