I got myself an
EXiM SPUP Screen Protector. From the reviews I've seen it seems to be one of the best.
Here are some before after screens for it too. On a LCD screen though, but I doubt it will look drastically different on an e-ink screen.
I (of cource) do not have my Kindle to test it with yet either.
I plan not to use it with a case since doubling the weight of a mobile device seems to me kinda counterproductive to its mobile use. I could care less about any scratches on the case, but the screen is a different issue. Therefore - screen protector.