I've tried giving The Way of Shadows a shot, but didn't like it. I'll check out the rest though.
An all time favorite. It's in a league of its own. But yeah, definitely read it.
I looked up what is considered grim dark and I can weigh in on what I have read.
ASOIAF. Good but I really don't consider it grim dark.
Poppy War. Weird one. The writing is on the level of a web novel almost, with like a professional editor cleaning it up. And then the first book is pretty light until you get to the end where it turns pretty shocking on that sets the tone for the rest of the series. It's pretty good and the fantasy inspired Chinese world building is interesting.
Sword of Truth. This one just came to me. It doesn't come up on any lists but This one is blatantly grim dark past the first book in my opinion and it's a massively popular series. I can't warn you off it enough. It's top to bottom thinly disguised rape-torture-porn. It's pretty vile and the fact that it's so popular is baffling.
Gantz. Another manga and almost the companion piece to Berserk. I could talk about this one for a couple hours because it's almost objectively one of the weirdest things ever made. It starts off really crappy and is super edgelordy. I kept reading because I knew it was popular and was desperately trying to discover why.
Is it good? There are parts that are good. There are parts that are really, really good. But there are also parts that are just abysmal. More than anything, I think it's interesting in terms of the creativity involved and what the writing says about the author and where he was in his life at that point in writing the series.
If endings are important to you though (I think I saw you mention AOT) then stay away. It has one of the unimaginably worst ending to any series ever.