There have been many posts regarding El Capitan freezing on reboot. First off, I'd like to say: Max108, you've been a godsend. A huge thank you to you.
You were absolutely right about deleting the EltimaSyncMate kext from System/Library/Extensions. However, I found one more culprit: in my case I also needed to rm -r System/Library/Extensions/ElmediaPlayer.kext
Thank you again, Max108