I use both. Plex is better for the less technical members of my family. I burned all my wife’s Workout DVDs and she uses it with ease. For HDR movies I prefer Kodi. My understanding is that plex transcodes from the originating machine where as Kodi will transcode on the machine that receives it - so the HDR films get transcoded on a machine with a graphics card.

For some systems they come as simple apps you can just fire up, or you can have the separate apps load up. Not hard to switch between them.