[Symmetry]

Ok, for an Ian M Banks fan specifically.

Alistair Reynolds has a number of good books which can capture some of the same darkness you'd find in part's of Banks's work. The Revelation Space books are great in their gothic way, and House of Suns has a lot of the galactic wonder aspects of the Culture books.

Ken MacLeod as a friend of Bank's and a good writer. His Fall Revolution books are probably the best known and explore various radical leftish ideas for organizing society across the nearish future.

And this last is a bit of an oddball but Leonard Richardson's Constellation Games was a book I really enjoyed that starts with aliens coming to Earth looking to help out and our protagonist, a video game reviewer, asking for alien games to review but ends up in a place that resonated with The Culture very strongly.