[robko]

I'll 2nd what AnemicOak said. There is no* e-ink reader that is going to be anywhere near as sturdy as your cell phone or tablet screen. I don't think there is much difference between brands on this, but Amazon are more likely to give a discount or replacement based on a broken screen even though their warranty doesn't cover it.
IMHO most cases are useless from an e-ink screen protection perspective since it seems to be twisting/bending that's the big killer and if you can flex the case it's not preventing much. I use a wood case if I'm traveling with my e-ink for that reason and I've never used a case during use (and never broke a screen).

*- I can't remember if there are any current small players that are using a flexible screen technology, but it's virtually non-existent