After scouring the internet for a solution I have finally found one that seems very good (and free!). Foxit PDF s is a clean user-friendly PDF reader and annotator. Using its cloud feature you can connect to Google Drive by logging in within Foxit. Then you can choose which folders to sync between Google Drive and Foxit. The amazing part is that any annotations you make to the PDFs are automatically synced with Google Drive and appear when you open the PDF through Drive in your web browser on anyputer!