Honestly, the quality of his writing gets much better as he gets more experienced. There isn't that much difference in quality in the first trilogy because from my understanding because when he writes his trilogies he writes them back to back in a batch and then releases them one by one.

Taking a drink every time you say grim and dark and now I can't feel my legs.

I really feel like Abercrombie only gets better, and most agree that the blade itself isn't his best work.

The original Mistborn trilogy is a great place to start reading Sanderson, but you could just as easily start with The Way of Kings. I started with Mistborn and was not disappointed!

I'll add that grimdark probably isn't what you think it is. It doesn't take itself too seriously and dark humor and satire are the scaffolding that holds it up. Even the words grim and dark (basically double-emphasizing the same thing) are used in a cheeky way to describe the over-the-top-ness of it all. If it's too serious, it ceases to be grimdark. If it stops taking itself seriously at all, it ceases to be grimdark. It rides a line.

I don't know where you are with your journey into fantasy but if you thought Joe's prose was plain then I do not reccomend anything made by Sanderson at all. Joe and George are both considered relatively prosey in popular modern fantasy, which maybe says more about the audience (definitely the #1 genre for ESL/YA).

I think "grim dark" is specific to fantasy. So compared to high fantasy where the good guy is good, and the.bad guy is bad. These books with morally grey characters are much more grim and dark. But yeah, compared to Stephen King, you won't be impressed by the darkness. It's kind of genre specific.

...You have to complete the trilogy and then everything will make sense. Book 2 is better than book 1 and book 3 is even better and will make the previews 2 books even better...I don't know if that makes sense but it kind of does. You got to see it as One Big Book cut into 3 parts.