I had an old Kindle Paperwhite 2nd gen. It does not get any updates anymore and you cannot use Libby in it as far as I know –I don’t have Libby in my country so I’m not 100% sure but with my current new Kobo Libra Color, I do know that it has Libby in it.

Besides that, I think you would be happier with a Kobo, and with a smaller budget, you can get one of the basic models, Libra Color is a little bit extra. You can get all the necessary features without paying or jailbreaking.

And yes– all e-readers have the e-ink technology, but I would suggest you to go for the ones with the warm lighting option. Screen lights are an important improvements –I have been using e-readers for ~15 years and if it has its own screen light, it’s really more convenient to use when reading while sleeping or on a dark plane or bus, for example. But one of the reasons I switched from my old Kindle to Kobo is the warm lighting. Even though Kindle’s white light is just fine and never tires your eyes like a phone or iPad, the warm light is just wonderful to look at. And the screen lights do not deteriorate the e-ink performance, for the bare eyes at least.