We recommend lit-html with the lit-element base class as a general-purpose library for building web components.
lit-html is feature complete, extremely lightweight and offers a great development experience.
Under the hood new Web Component APIs such as Constructable Stylesheets are used when they are available. As browser support improves, you get performance improvements for free.
To get started, we recommend using our project scaffolding:
npm init @open-wc
Check out the code examples page for a collection of best practices and design patterns.