Poppler and its integration with Emacs via pdf-tools has dramatically improved my PDF reading and annotation powers. Since I started using it about 5 years ago,

Poppler and its integration with Emacs via pdf-tools has dramatically improved my PDF reading and annotation powers. Since I started using it about 5 years ago, for the first time in over 30 years I prefer reading and annotating papers in digital form (as opposed to just storing and searching, which happened over 10 years ago). Recently I started using Amazon scribe as well, though I wish it was a more hackable hardware (without Amazon as an intermediate) so I could further optimize my workflows.