I like that it is built with security in mind from day one. It's also very extensible so you can customize almost anything about your application. The documentation could be better at times but there are some really helpful people out here who will help you along the way if needed. If you're looking for an MVC framework then sails would likely not fit what you need because of its lack of conventions. For me this was more of a personal preference than something objective. We were solving our own problems by building a new web app using node/express. What we ended up doing was creating our own convention system which solved most issues we had (which weren't many).