I have been using handlebars for years now for small production projects. For example a single page of digital signage displaying the output of a JSON endpoint. It's been great for that but I feel like I may want to experiment with something new that can optimize my images at build time, gzip etc... What else out there these days can be used for this purpose? React/Next is overkill and to be frank not my skillset.
I've been using Eta: <a href="https://eta.js.org/" rel="nofollow">https://eta.js.org/</a><p>It doesn't do gzip or image optimization, but such features might be better suited as server middlewares separate from the template engine.
Try Mustache <a href="https://mustache.github.io/" rel="nofollow">https://mustache.github.io/</a><p>Planing to use it on new SEO project <a href="https://vim.expert" rel="nofollow">https://vim.expert</a>
Handlebars seems to me to be the right level of abstraction - it's done for me quite well in the past. And if I reach out for a web framework again I think I will not stray far.
Good luck with your search