I can't speak for plyr as I am not familiar with their project. What I like about indigo is the way modules are structured, the initial file (indigo-player.js) loads the needed code in order to provide playback, it's basically a mono repo. I've spent a fair amount of time on state management too, meaning you have a well defined & standardized API no matter whether you play DASH/HLS or use FreeWheel / Google IMA ads.

Edit: the state interface can be found here: https://github.com/matvp91/indigo-player/blob/master/src/ext...