I am playing both 11 and 14 at the moment, but what would keep me around would be for them make old content far more accessable like they did with CoP.
I am a bit of an odd ball player, I play for the story and for BLM. BLM is my one and only job, I don't care for any others, but I am a casual player and I am in the UK. It is very hard for me to get most stuff done but there is so much I want to do and now some of it seems impossible. I would love to do the following:
Limbus: For whatever story content exists there, get items for AF1+1, get Atmacite of the Ultimate.
Dynamis: I have a full set of currency, but would like to get my Sorcerer's Belt and the AF2-1 items and make it the old way before making it +2.
ZM+CoP: I have completed both of these but have done none of the continuation missions, I would love to do stuff like fight Bauhamut.
ToAU: Never got anywhere in this, still on mission 15, doubt I could ever get the people to do this these days.
Assault: Kinda pointless but I would love to run and complete each and every assault atleast once and also complete the Yigit armor set, again doubt I can find anyone to do this.
Salvage: Again would LOVE Morrigan's set but probally impossible.
Weapons: Would love to make these but totally out the reach of casual players like my self.
Things I did like (sort of) were the Magian's Weapons, for me as a BLM anway. It was stuff I could do on my own without bothering others, my only real problem was the number of mobs you need, what does killing 250 mobs prove? Then needing to do it 5-6 times for each staff, for 7 staves. How is it fun? It was pure tedium, 25 mobs would have been more than enough.
The best was our AF3 though, easy enough to get the base items, and whilst the +1 and +2 items needed a group, it was only ever a small group and you were (almost) always rewarded with drops, and the number of drops needed was not out of the world. It was a reachable goal and it was fun to help our pals out.
Adoulin on the other hand I really am not a fan off, I need to go wack trees or stones for hours on end, in the hope of getting a drop, that I need 3 of, so that I can make something, so that I can access something else, where I might get a drop and maybe some items to give it a random upgrade... Really, anything random is awfull! If I have worked hard for something I want pay off. I do not go to work and then have my boss /random to see how much I get paid that month. Give me fixed or selectable upgrades, like AF3 armor
It is always hard to stay motivated for things when /random is involved.
14 on the other hand (so far atleast) is to easy and anti-social. I have just unlocked BLM in it and apart from a few story missions and dungeons I have not even teamed up with anyone, and when I have no one has talked, I am not even in a LS. It feels more like I am playing Legend of Zelda with some co-op dungeons thrown in. I miss the working with others from 11.