I like that it we can use either zip archives or img files with jsdosbox-- and that the setup is pretty straightforward.

Here's a guide I hacked together a couple of months ago for comparison: http://atechdad.com/how-to-jsdosbox/

em-dosbox uses emscripten's packager by default, but it doesn't have to. Anything that can dump files into an emscripten virtual filesystem will work. The Internet Archive's loader uses .zip file bundles via BrowserFS: https://github.com/jvilk/BrowserFS