Even though I am genuinely intrigued by the genre as I truly believe we are headed towards a cyberpunk world,
most of the books left me disappointed so far: shallow plots, shallow character development.
Cyberpunk and steampunk are both fascinating literary styling/function/concept milieus that have never seemed to gel properly entirely on their own, either on the page or on the screen.
I don't think that I have ever read a really great book that is commonly placed in either genre, partly because of what you mentioned above, but mostly because science fiction has already "been there and done that" so many times, and so much better. There are literally hundreds of books that have sat on the science fiction shelves for decades that were in fact, although not in name, exemplars of these "new" genres. Film, which might seem to be a more friendly vehicle, has generally been disappointing, too, although there have been some successes.
The space faring voyager landing on the planet with a slightly pre- or post-Industrial Revolution level of technology has been a stock in trade since the beginning. Also, for me personally, the fact that magic is so prevalent in mainstream steampunk often makes it boring, because it usually seems like it is a plot crutch that weakens the story rather than strengthens it. One successful but very strange advanced example might be “Perdido Street Station” by Mieville.
If I had to pick a single favorite steampunk book, it would probably be “Leviathan” by Westerfeld because he managed to weave the conceptualization of a steampunk into a larger narrative. Much more interesting to me is something like Alastair Reynolds’ “Terminal World” with its “technology gradients” wherein there is a “steampunk” band among numerous others.
Drawing a line between cyberpunk and science fiction is very difficult, if not impossible. Almost as soon as the idea of humanoid robots was introduced, the merging and intermingling of meat intelligence and machine intelligence has been a very common theme, or at least undercurrent, of many, if not most, stories set in the future. Do the Terminator and Matrix movies fall inside or outside of this category?
Picking my favorite book, commonly considered as a mainstay in this genre, I would probably select “Snow Crash” by Stephenson, but which is already showing its age. Somewhat tangential but far more advanced, I would again give a nod to Reynolds and his magnificent “Revelation Space” where all the lines are blurred, and additionally there is a huge ancient mysterious non-living “system” which has ill intentions towards pretty much all living intelligence.
And it is hard to believe that this is almost 20 years old now:
https://www.wired.com/2000/04/joy-2/