Getting access to all the weapon skills is so much faster, which makes trying out new builds a thousand times easier.
Not having to find and speak to the quest giver before I can do the quest is great. I like just having to get into their radius without having to track them down before and after.
I'm a big explorer, so I really appreciate the rewards for exploring the maps (and the compass pointing me towards the things I missed).
The jumping puzzles are amazing.
The free mount not being a boring-ass horse is pretty cool. Mounts having different abilities is also cool. Not having to spend 120 real days upgrading your mounts is really nice.
Getting experience from harvesting and crafting. Not having to spend real-time months researching things to craft them.
Underwater exploration. Yeah, underwater combat is kind of a pain, but it's still cool to have the option.
The directed story mode complete with boss fights in instances that can be done solo.
Classes are all totally different from each other; there are no "meta" skills for a specific role no matter what class you're playing (eg, unstable wall, aggressive warhorn).
Enough skill points in the game to learn every skill and every specialization, along with the ability to switch builds on the fly just whenever (without having to go back to a shrine and pay to do it).
I'm not sure how I feel about having a centralized auction house. A lot of my endgame in ESO was shopping and flipping valuable things from one trader to another, but I have to admit it's really handy to just be able to go buy a bunch of crafting materials in any city for the lowest available price.
Like, I could just keep going; there are so many things, both little and big, that I love about GW2. But for some reason, I just can't get into it. Maybe it's that it levels me up so fast that I don't get to really enjoy the view and learn the class. Maybe it's because the elite specializations change the class so dramatically that most of what I did learn during leveling is immediately obsolete at 80. Maybe it's because the combat feels kind of clunky due to being a weird hybrid of action combat and tab targeting. Maybe it's how complicated the buff system is, that I can't really wrap my brain around all the different boons and when I need them. None of those are really big deals, just quirks of the game that make it unique, like all games have. But it's not doing the same thing that ESO did for me.