1. Feeling like a DPS with heavy support options, Personally I'd argue tanks need more fun rotations but tanks at least have semi interesting dps kits compared to healer.
2. being able to save people, while healers are obviously capable of this, tanks are actually very good at preventing party members from going down if you're weary of your party members which i like, because it gives me something to look out for.
3. controlling the pace of dungeons, I like to wall to wall I know i can do it effectively too, being a dps or healer it's frustrating when a tank doesn't pull a lot and the dungeon takes ages.
4. feeling like the "main character" this ones more silly, but when you have aggro it obviously "feels" like you're the actual threat which i personally prefer over being on the side lines.

Personally I think tanking is fun in ff14 but i will argue that they should have better dps options still it's lacking.