eBike technology explained

Hey everyone!

I was just reading up on some of the latest eBike tech advancements, and it got me thinking. With so many different motor types, battery chemistries, and sensor systems out there now, it feels like the tech is evolving super fast. What's one piece of eBike technology you've found genuinely revolutionary or perhaps still a bit confusing? I'm particularly interested in hearing about mid-drive vs. hub motor experiences on varied terrain!