"Best" is subjective but one of the most interesting talks I've seen this year is one on Plain Text:
https://www.youtube.com/watch?v=gd5uJ7Nlvvo
And although it's almost ten years old, Gary Bernhardt's "Birth and Death of Javascript" is one I re-watch at least twice a year and frequently recommend (and it's unreal how prescient he is in this talk -- I just hope the references to the Bay Area exclusion zone and us all running for our lives isn't as accurate as his prediction of the raise of WASM):
https://www.destroyallsoftware.com/talks/the-birth-and-death...
