Comet and a scrubby
Clean them with vinegar, baking soda, and salt. Stubborn mineral buildup on glass shower doors is no competition for a few common household ingredients—white vinegar, baking soda, and salt. Spray vinegar on the door and let it sit for a few minutes. Next, create a paste with equal amounts of baking soda and salt. Rub the door with the paste and rinse clean and you should have a sparkling clean door.
I have glass doors, and squeegee them after each shower. If there is any build-up, I like Aunt Fannie's vinegar gel, or Scrubbing Bubbles.
I use Scrubbing Bubbles or soft scrub.
Cut a grapefruit in half, cover with kosher salt and use as a scrubber.
Lysol Power Scum cleaner in the blue trigger spray bottle with a Magic Eraser or a scrub brush.
Wet & forget shower for a slower, no scrub solution. You can use 2x a week to accelerate the cleaning process then once a week to keep it clean.