As of Aug. 2020, this list merges the following internet lists that include books commonly tagged as or near 'hard science fiction': Hugo, BSFA, NPR 2011 SF & Fantasy, Arthur C. Clarke Award, Reddit Fantasy 100 List, Goodreads SF/Fa Top 300, Misc. Internet Lists, Locus Fantasy Award, Nebula, Locus Scifi Awad, Hugo (Retro), Reddit Best Scifi List, Top 200 Sci-Fi Books, Top 100 Sci-Fi Books [double counted with Top 200 Sci-Fi Books, given that it is a meta list itself].
Of the top 100 here, I have consumed about ~75% in some form (85%+ by reading) and of the top 250 about ~50%.
Ignoring the top 10, I've included a column of "Tim's opinions about whether this book is notably underrated/overrated *relative to this list*."