Been using Stencil for the past year or so as a way of extending our Angular app with client-specific apps (eventually looking to open this up to clients to upload their own components / apps).

Overall it's done a good job but I still find the build system somewhat esoteric (there are a number of different approaches and it took some effort to figure out the right one for our use case).

I have noticed development has slowed down over the past couple months: https://github.com/ionic-team/stencil/graphs/commit-activity

Hoping it's more a case of it approaching maturity as opposed to it being neglected...