They save your time in the long run. If you going to write just one or two papers you might not need to worry about them. But if you are going to working as academics for a longer time it is wise to invest in one these tools. As to the choice of the tools don think that it is a simple decision. You should carefully investigate which of them serve your purpose. Every one of them have their strengths and weaknesses. I have tried all the 4 reference managers you have mentioned. All of them does the job of you mentioned very well. But as you use them more and more you needs grow and change. MENDELEY I have followed this tool since its beta state around 28. It is fairly good tool. The major advantage of it is has social networking; good searching tools; can rename PDF files automatically; can also work with Latex. Indeed from all the 4 it is the best fit with the Latex system. The reference entries have no attachment anymore. It gets its reference data from Google Scholar. It is a hit and miss and the metadata extraction is just useless. If you want to learn about its weaknesses check their support page there are a lot of weaknesses to it. One of the most annoying problem was every time I move around the library the between the reference and the PDF gets lost. Endnote and Zotero these are matured products. Zotero is open; has vibrantmunity. Personally I don stick with them because they are terrible with Latex. Sente PDF reading at its best the annotation system in this reader is heavenly. But you better skip this because its development seems you are going to use the tool for a longer time my rmendation is either Zotero or Bookends. If you are looking for a simple task for a shorter time still Zotero. ordered-list If you are using Windows Qiqq seems one of the top tools for reference management and information structuring Mendeley vs Citavi vs Qiqq (also Sente and Bookends) s