AppJS, one of the oldest frameworks in this space, now deprecated in favor of deskshell, which, unfortunately, seems also to have lost momentum. Personally, I liked the approach of this one, as it routed content in a way very similar to web MVC frameworks, making porting web apps from node.js much more transparent. However, unless development picks up again, it's probably not a good choice for new projects.
NW.js, formerly node-webkit, is one of the most popular and mature options today. It offers the best assortment of features, great community support, and easily searchable online questions. As it's been the go-to option for this type of application, it already has an impressive list of mature applications, Intel XDK cross-platform mobile IDE, and even several video games.
Electron.js, originally built for GitHub's Atom editor, is brand new, but it's already really popular. Its philosophy sits somewhere between NW.js and AppJS. Like AppJS, it cleanly separates front-end from back-end (which run in separate processes and can only communicate via sockets), but it provides no built-in MVC routing framework. Electron.js probably has the most commercial momentum at the moment, despite being not quite as feature-rich or mature as NW.js, and forms the basis for Microsoft's new Visual Studio Code and Slack's desktop presence. Also, Electron.js made the bold move of supporting io.js instead of node.js, which means it supports a few more cutting-edge features of JavaScript than the others, while (at least in theory) supporting backward compatibility.
