Christ, what an imagination you have
I once quoted Zanzibar's Bernie to Rudy Rucker in an email, but that's another story. Stand on Zanzibar lodged itself in my brain lo these decades ago, and never left. Zanzibar and The Sheep Look Up. Say the word "dystopian" to me and I'll immediately think of those two stories. Their factual basis hasn't aged all that well (Z is set in 2010), but who cares in the face of great storytelling?
Another Brunner work that had an impact on me is Shockwave Rider, probably the first story of computer hacking I ever read. It was an eye-opener, as much for the basic idea that those mysterious temples of computing could be penetrated and suborned, as much for the specific techniques he imagined (and fairly well).