For me, some of the big ones are;
-Great graphics and animations. I don't remember FFXI looking so great when it came out, but this game looks fantastic.
- Ability to solo effectively. This does a lot to make me not feel like a ponce, not to mention it saves a ton of time if I only have a couple hours to play.
- Ability to see multiple linkshell chats going on at once. That way I know which is the busiest and I never have to stop chatting.
- No exp loss when dying. Probably one of my most hated aspects of FFXI is thankfully gone in this. Any progress I make is permanent. Although I do think the rate your gear deteriorates is a little much, and I hope they adjust it in a future update.
- Much larger areas that I can traverse without zoning. Helps immerse me in the world. I quickly quit Age of Conan once I realized how small and instanced the areas were.
- Crafting is much more fun, complex, and rewarding. It feels like it's actually worth the effort, and not just a side novelty.