No e-ink device has, or can have, a backlight. So to answer your question - only the Paperwhite and the Voyage can be read in the dark without an external light. The Voyage has the highest print resolution, so it should be the easiest on your eyes.
Similarly, you may ask, what is a built in light on a Kindle?
Basic kindle, with no built-in light can't be used in a pitch dark room. You would require day-light or an artificial illumination source if you need to read during night, same as the paperback. The kindles with built-in light (backlit) are similar to our mobile phones.
Are any Kindles backlit?
Amazon Kindle 2016, First Take: Affordable, but backlight-free. Amazon's latest Kindle is being presented as the company's most affordable e-reader ever. The new entry-level Kindle has a 167ppi E Ink screen, compared to 300ppi in the more expensive Paperwhite, Voyage and Oasis models. It also lacks a backlight.
Can I turn the brightness up on my Kindle?
To adjust the screen light while reading, tap the top of the screen to show the toolbar, and then tap the Quick Actions icon . To adjust screen brightness, slide your finger along or tap the scale to reach the desired setting. On Kindle Paperwhite, you can also tap Max to quickly turn the light to maximum brightness.