Express has a minimalistic approach and seems to be a classic and straightforward framework for coding architecture. Creating a robust API is quick and easy with a myriad of HTTP utility methods and middleware at your disposal.
Koa is a new web framework designed by the team behind Express, which aims to be a smaller, more expressive, and more robust foundation for web applications and APIs. By leveraging async functions, Koa allows you to ditch callbacks and greatly increase error-handling. Koa does not bundle any middleware within its core, and it provides an elegant suite of methods that make writing servers fast and enjoyable.
Sails is a MVC framework for Node.js, designed to emulate the familiar MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with a scalable, service-oriented architecture.
LoopBack is a highly extensible, open-source Node.js and TypeScript framework based on Express that enables you to quickly create APIs and microservices composed from backend systems such as databases and SOAP or REST services.