Here are some from the top of my head:

- Companion interactions and storylines.
While I'd love to have more of them, what we had really was the essense of my experience! I kid you not, I wasn't able to let go of the game when I first started playing, because I really, really, really wanted to see if the companions had something else to say if I just finished one more quest or one more long rest. I mean, I have a job, but I didn't go to bed before sunrise after being so beat up and horrified about the idea that I'll have my first meating in just a few hours.

- Astarion.
Oh my gosh, this character was so interesting! All the kudos to the writer for making a character with so many nuances. It was refreshing to see a character who doesn't say everything explicitly and who at times is an unreliable narrator. All directions to his storyline felt equally worth to be told, which was really impressive. And Neil Newbon, gee, how can anyone even be that talented! While I was playing it suddenly clicked in my head that I've heard his voice in so many games during the years, and he has always been phenomenal. Now I just have this terrible realization that his job is the best in the world and I start to question my life choises.

- The eyes.
Maybe this is a weird thing to be so excited about, but... I've been a gamer my whole life, so I've seen the games evolve from glumsy pixel characters to something I never could have even dreamed of when I was a kid. So when I was creating the character I remember thinking that it's nice to pick a color for their eyes, but that I probably wouldn't even see it during the gameplay. And then when I saw the first dialogue cut scene with one of the companions I realized, first, that I actually do get to see their beautiful eyes and, secondly, their eyes move during dialogue! I tell you, I was so much more impressed than a person probably should have, and still keep telling my gamer friends how awesome time we are living to finally see the eyes move! (Sure, BG3 isn't the first one, but it was the first one where it really hit me and now I'm such a happy geek!)

- The combat gameplay.
I haven't yet figured out why I enjoy the combat so much in this game. I normally don't! Normally in turn based games the moment the combat area loads, I start to realize I'm going to be just utterly annoyed struggling through it. But BG3's combat proved to be actually enjoyable for me during the whole game. Maybe it was the feeling that I have multiple solutions to the situations and I'm not going to realize 20 turns from now that I started the wrong way. It wasn't too difficult, but it was varied enough to encourage me to try different things. Whenever I wanted to spice things up, I just changed the party.