Riot.js is like a minimal version of React.js that I've found quite easy to use

I'm honestly not using any non-mainstream framework yet, but I'm at the window waiting for Aurelia. It seems really well engineered, and I need to learn a new framework anyway if I want to jump to Angular 2... They're hosting an AMA right now here on Hash node (hashnode.com/ama/with-aurelia-team-cijv67apt000o5…), they're very responsive and Rob Eisenberg seems to be a really nice person; it's good to have the chance to know "the man behind". Their business model is also intriguing. Anyway, after all these sweet words from me... I still want to wait for a release candidate (and hopefully a full fledged published book) before considering it for a project.

I'm building a large, complex web app in Aurelia right now, with a .NET / Azure back-end. Going great so far! A little worried about the SEO implications of Google not being able to see Aurelia views correctly, but will cross that bridge when we get closer to production.

One of my projects is using a custom-built framework in Dart, another one is in pure jQuery, even components are built in pure jQuery (long before web components were a viable option), another project I did was in ExtJS3 or later rebranded to Sencha, another project I'm using Polymer Dart.