I'd put Banks in the Asimov/Stephenson tier at best. His ideas were brilliant enough to sustain a long series - but not one book in it actually makes for a good read. Neal Asher doesn't have anything like the same ambition, but Hilldiggers is a better Culture novel than any of the actual Culture novels if you actually want to read and enjoy it.
I am glad someone else has the same view point: Asimov and Stephenson are great hard sci-fi, but they can't write characters. Except Stephenson COULD, and did in Snow Crash and Diamong Age to some degree, but then stopped being interested in it. While VV had good characters in his books, even though I would argue he wasn't "excellent" at it either, and maybe Stephenson even surpassed VV in characters/story in Snow Crash.
I can't really judge Asimov - so many people stole from him that he just reads like War & Peace to me in the sense that it was probably awesome and novel at some point, but at this point it's just a little stale, even though Foundation was still cool...at least the first few books.
With that said, I don't put VV above Stephenson. Maybe above Gibson because I really appreciate the technical details, but not quite sure. To me VV, Stephenson, and Gibson are all the absolute top tier, at least in the sci fi realm. No one even comes close, as cool as some one offs by other authors, like Forever War, are.
I've so far only read Consider Phlebas, and while it's an interesting dystopia where humans have no purpose, and machines could do everything (if allowed), it's not an actual interesting story.
It's like he had the idea for the dystopia, with the main character fighting against the machines. And then tried to write a story around it. The central idea is interesting I guess, but the story built around it is not.
It doesn't help that the fight is futile, the machines as described are so powerful humanity doesn't stand a chance, so what kind of story can you make?
it's an interesting dystopia where humans have no purpose
Unfortunately every single one of his books has this problem. It's like all of his novels are written from the perspective of the protagonist's housecat.