Paid resource
发展汉语 (Developing Chinese)
My notes
I didn't use it heavily myself, but almost every university language programme in China uses it, so there's clearly something there. The people I know who did use it still supplemented with HSK books, so I'd treat it as a parallel resource rather than a replacement. Worth picking up if you want a more academic framing of the grammar.
发展汉语 takes a more academic approach to grammar than the HSK books, which I found useful for understanding why certain patterns worked rather than just accepting that they did. I didn't use it as my primary resource, but having it alongside the HSK materials meant I could cross-reference explanations when a grammar point wasn't landing. If you're studying formally or through a university programme, treat it as a reference rather than a cover-to-cover read — supplementing, not replacing, the HSK books.