So I tend to highlight books when I find a particularly impactful, funny, or otherwise noteworthy moment of prose. I can say with confidence that the author I have highlighted the most is Yuu Tanaka of **Reincarnated as a Sword **fame. Just a great mix of action, dialog, humor... a perfect all-rounder. I have no issue reading and re-reading and re-re-rereading his books.

Honorable mention goes to Kaye Ng, the author of The Villainess Is An SS+ Rank Adventurer. She is incredibly witty with her dialog. So much so that even when she reuses jokes they continue to have their punch. A few random examples from the 3rd book with absolutely no context:

“What are your current bribery rates?”

“Very low. I have no standards whatsoever.”

Coppelia gasped, her hands covering her mouth. “You mean … there are people who don't design their own death corridors?”

“You're going to stick your sword into the magically warded keyhole full of explosives, aren't you?”

The first 9 volumes of Tearmoon Empire were incredible and the witty prose reached at times that of the likes of Prattchett and Adams.

Other than that it depends on the definition of "writing style". If we include stuff like how thought out things are then I absolutely have to mention Miya Kazuki. It's very, very seldom that I have the feeling in the light novel space that an author has a detailed idea of how the story will progress. In most cases, I get the impression that each chapter is written as they come. I have that mental image of an author beings pulled along by the story like some scrawny individual being pulled along by a large dog. It's probably a side effect of the web novel origins of most titles. So when a series looks like it was planned out in advance, and plot points are introduced in previous volumes instead of paragraphs, it stands out. The Fanbooks Q&A sessions were especially eye-opening when she described how detailed her plot outline from beginning to end was before she even posted the first web novel chapter online.