I have a Kindle and love it. I have the cheapest model you can get, but I have the Kindle app on my tablet. I do all my reading on the tablet. It is back lit, and I see fine with it. The font size can be enlarged on any Kindle model.
I got my daughter a Kindle Paperwhite for her last birthday, and she loves it a lot. The screen is back lit. It has a touchscreen. It operates over wi-fi. You hook it up to your home wi-fi router, and you’re good to go.
Amazon offers literally millions of free books, and there are some really good ones. Remember though, they are in business to make money, so they want you to buy books. They don’t make it easy to find the free books, which are mostly classics since they’re out of copyright protection and in the public domain.
Some local libraries offer books over the Kindle. Of course, those are free.
If you have trouble reading in low light, I recommend you ask your friends who have a Kindle to let you take a look at theirs and test your reading ability.
The Kindle Paperwhite is what I recommend the highest.