I'm using RJSX-mode + emmet mode for JSX. RJSX is a fork of js2-mode so it handles normal js just as well. It has built-in linting that works great but you may still want to set up eslint if there's a need for it. `web-mode` is the undisputed best mode for HTML and again you can pair it with emmet-mode to write even faster.

If you're looking for 'intelligent' auto-completion like IntelliJ Emacs is probably not for you, but I think most people choose Emacs for its keybindings and workflow anyway. The shortcomings are definitely worth it imo.