The way people use laptops, the screens are generally much lower than they should be for good ergonomics.

iPads/Kindles are better because they're smaller and lighter so you can position them with far greater flexibility.

The laptop is better in many situations as the screen stands on its own.

When reading in bed I use a stand to hold my Kindle at the best position. I would need a much heavier stand to be able to do that with my iPad.