As someone with autism and ADHD
1. Like crymaen commented: Flashpoints. I hardly ever do the longer ones (besides when going through story) with non stealth classes as I lose focus easily due my ADHD, some type of "easy mode" or "fast mode" or "turn off level sync on solo" would be really nice.
2. Lowkey falls on QoL but relates to my ADHD, autism and OCD symptoms: general organizing
a. Favorite recipes for crafting and recipe search, scrolling through all the recipes just to find the ones you use the most is tedious and makes me loathe crafting and as the UI can be kinda messy due to the colors (I personally find blue/white super muddy combination), there's a lot of crafting wrong items and getting frustrated due to it.
b. Favorite items. While you can just buy things back at the vendor, accidentally selling something you didn't want to without realizing in a hurry or such can really be nerve wrecking. So having some kind of confirmation system for "do you really want to sell this item?" would be nice.
3. UI color schemes. I really, really dislike the blue/dark blue/white color scheme. I find it really hard to read and see most of the times even though I'm not colorblind, just have eyeglasses. Having different color schemes would be be welcome.