Livre d'Or

Yeah, people-driven versus difficult maths doesn't quite precisely get the distinction. The best Egan stories, I agree, are those which explore an interesting idea, often with a mathematical or other sciencey underpinning, but sometimes more philosophical than anything else, through a viewpoint character who is sympathetic enough for the reader to relate, but not particularly vivid. Actually my absolute favourite Egan is Orphanogenesis (though I wasn't quite so keen on the expansion into Diaspora). The thing I loved about it (and it shows up in some of Egan's other IMO best writing) was that he created characters I cared about, who were absolutely and indisputably non-human.