Update: I wound up building a sample project in both this weekend. For what I was trying to build (a robust, scalable API) loopback was much better. I wasn't as

Update: I wound up building a sample project in both this weekend. For what I was trying to build (a robust, scalable API) loopback was much better. I wasn't as interested in generating server side rendered pages, although you can do it in loopback since its just built on express. Loopback seemed much better for making a serious project with monitoring, devops, debugging, deployments and less 'magic'. Sails definitely wasnt bad; it is more popular and its docs were a little better, but ultimately I had to dive into the code in both frameworks, and loopback's codebase was easier to understand. If you're developing primarily an API in node.js I would definitely recommend it.