1). Main Story Quests - The thing I enjoy most in FFXIV, I feel it needs far more love than it got in 3.1.

2). Addon API - I can't believe it's been so long and the development team has yet to bring us a basic addon API, we haven't even got any information recently. To top it all off, a player has developed an alpha for a addon framework, before SE has managed anything.

3). Instanced Content - Raids (including 24 mans) > Trials > Dungeons.

4). Glamour - Things like gear, hairstyles, mounts, minions and so on.

5). PvP Content - Can't say I care too much for PvP in its current state, and won't care unless they make major overhauls in regards to balance.

6). Gold Saucer Content - Minigames like Lov, Triple Triad and Chocobo Racing.

7). New "SE designed" content - SE has yet to prove they can actually develop something new and have it be fun and exciting, so this is at the bottom for me. I'd prefer they just took a look at other MMOs, saw what looks good, and then implemented it in FFXIV. cough Legion artifact weapons cough