The latest bog standard kindle is back lit now, the difference between it and the paperwhite in terms of light is really non existant (the kindle has 4led's, the paperwhite has 5, you won't notice, we have one of each and cannot tell)
That's interesting. I have one of the very early paperwhites and it's starting to show it's age - the battery doesn't last as long as it did and if it died I would want to replace it straight away.
As I don't read in the bath, it sounds like the cheapest kindle would be fine for me, which I'm pleased with as I notice that they've recently gone up by £10, which isn't that bad anyway, as it is probably the only price rise since they were launched and I must have got my first kindle (a kindle keyboard) around 10 years ago now.
On the subject of actual kindle vs phone/tablet apps, there really is no comparison in the reading experience. A kindle is very book like, while the lighting on a screen is just wrong, it's still a screen, too bright in darkness, but difficult to see in bright sunlight, plus the battery doesn't last and there's still the potential distraction of tripping off into social media/websites etc.