I tried Zotero, Mendeley, and self-managed spreadsheets. Finally, when I tried paperpile, for the first time I felt like these people truly understood people like us in grad school. I use google drive to store my papers, use the chrome extension to easily add papers to my library, use the BibTeX export for citations, iPad to read and annotate papers, tag and search papers, and many other features that make my life much simpler. At first, I was hesitant because it was not free, but with the student discount, it's very reasonable. In fact, I have recommended paperpile to so many people and many have subscribed and are very happy as well. Don't just take my word for it -- Try it out. I know I probably sound like they paid me, but they didn't. I am just a very happy customer and I think they deserve recognition.
