Cross-device PDF reader with highlighting?

Iā€™d like to use books bought on raywenderlich.com in the PDF format, however this is proving to be deeply inconvenient.

I need a system that will:

  • have PDF reader apps on all iOS devices and the iMac
  • allow highlighting of PDF documents
  • synchronize PDF document highlights accross all devices

iBooks no longer allows PDF highlighting and Kindle does not appear to sync imported PDF documents between devices.

Any suggestions are welcome.

@evs718 Thank you for your feedback - much appreciated!