Diaspora by Greg Egan: Hard sci-fi about quite a few things but mostly centering around the nature of consciousness. Although it is about a number of different big ideas and spans a long, long time, the story gels together really well. A lot of the physics and maths stuff flew over my head, but the plot is followable.
Leviathan Wakes(Expanse #1) by James S. A. Corey: First book of the Expanse series. Entertaining story and intriguing start of the series– I’ll definitely read on.