Can't be bothered to list them all so I'll just focus on the one I like the most. And if I'm going to just pick one, out of all the things, then that would probably be the combat animations. That's what I'm liking the most for the moment anyway.
Maybe not the quality of the animations though (which is still mostly superb) but rather the WIDTH of them. Instead of having one animation for almost every single one of your attacks they are actually completely unique in this game, every single one of them. And then there are so many abilities to boot. To me this means a great deal cause it really makes every single fight, even small ones while questing, so much more enjoyable to watch when there's such a wide array of things that can happen. Also, it just plain sucks when you wanna try out a different class but everything still feels so familiar in the gameplay. The work they've done with the animations really impressed me.
Another thing: In WoW (yeah I know, the comparisons are getting tedious but just hear me out here) it probably didn't matter cause the damn damage numbers have gotten so huge and abundant that you rarely see what your character is doing anyway. In TOR I find the numbers pretty hard to notice most of the time, so it's basically the other way around: You see the action that's going on, and not numbers.