I was and am a heavy Skim user (http://skim-app.sourceforge.net/ http://skim-app.sourceforge.net/) -- on Macs, I've found it to be a quick and snappy alternativ

I was and am a heavy Skim user (http://skim-app.sourceforge.net/ http://skim-app.sourceforge.net/) -- on Macs, I've found it to be a quick and snappy alternative to Preview or Acrobat for reading and marking PDFs. 10.12 broke the UI for text annotations (the bugs mainly had to do with on-screen refresh). While 10.12.2 partially fixed these problems, it introduced others. Here's one: open any pdf in Preview in 10.12.2, choose the Rectangular Selection tool, and try to copy a rectangle from your PDF. On my own machines running 10.12.2 as well as the couple machines I've tried in the Apple Store, inevitably this leads the whole page to go blank. AFAIK the file is not affected, it's purely a UI thing, but bugs like this make the software very annoying to use at the very least.