Vinegar. All I have to do is wipe them down once a month maybe let a vinegar soaked rag sit on some tough spots, but no scrubbing or scrapping required.
Do you dilute with water? Or just soak paper towels or clean rags in straight vinegar and just let sit on the glass top?
I usually try to scrape with an alge scrubber to get the stains that I can feel with my fingers, but I know the hardwater stains are still there.

