Aside from all the exciting changes coming to the battle and armoury systems that were previously announced, here are my personal favorites:

In-Game Achievement Management
YES!!! I am an achievement junkie! I was first introduced to achievements in Warhammer, and got officially hooked when they implemented the system in WoW. I realize that FFXIV has been tracking our achievements since day one, but you can currently only find them in your history on the Lodestone. It will be nice to be able to see them in game.

Action Bar Revisions
I know this ties into the new battle system, but it's also a UI issue and the action bars are something that's been a real source of contention for me. I'm tired of the clunkiness, having to flip through 3 different bars, and reset abilities. I'm glad this is something they're prioritizing.

Ifrit Battle
Our first primal! Will Summoner be an option with the new job system? Can't wait!

Auction House?
Looks like the jury is still out on replacing the market wards with a traditional auction house. They're still open to the idea and are currently making a final decision.

Mount System
Kind of odd how FFXIV is STILL loathe to come out and say chocobos, for some reason. I'll just be glad to have something more than anima and a pair of worn out shoes.

Configuration Menu Improvements
Settings done via text commands will now also be available in the configuration menu. Finally. I'm getting too old to remember a giant list of text commands anymore, LOL.

Custom Chat Log Tabs
The system is pretty much already in place. You can make your own windows. I've never understood why you can't make your own tabs. This is something I've nitpicked about for a while.