My recommendation for new hard SciFi is anything by Alastair Reynolds, from his “Revelation Space” universe. His book, “Pushing Ice”, isn’t too shabby either. “Galactic North” is a collection of several novellas and short stories set in this universe and is a good start to understanding the social groups within that universe and the settings for many of his other stories. You can jump straight into Revelation Space, but he uses a lot of jargon and shorthand in passing, which can make the action difficult to follow.
The dialogue is prolix and for me, fails the “do people talk like this?” test, but still, he creates a Gothic space fantasy world that feels like a world should, where the inhabitants use nano and femto tech for extreme body modification and neural manipulation. It feels more real to me, than say, Larry Niven’s Known Space stories, which to me feel like 1960s Los Angeles, only with Puppeteer hulls and stasis fields. Reynolds’s universe is incredibly Gothic, alien and at times, quite horrifying. I love it.
Another hard SciFi author you might want to try is Charles Stross. Stross utilizes elements of hard SciFi in his work, but I think his primary purpose is to take the piss out of several literary and other genres and tropes. Which he does quite well. As very funny and well done as I think his books, “Singularity Sky”, “The Atrocity Archives”, and “The Jennifer Morgue” are, I am really waiting for some ideas of his own that don’t revolve around satirizing other peoples’ works. “Singularity Sky”, in particular, has a hilarious takedown of the “Honor Harrington” school of space opera technobabble.
Finally, though I wouldn’t call it Hard SciFi, you really owe it to yourself to check out Iain Banks’s novels about “the Culture.” Delightful Sci-Fi universe with, for a change, well written dialogue and characters deeper than cardboard.