I would start with
https://www.mobileread.com/eink/ for a nice comparison of all of the different readers on the market. All of the readers are equally easy to load using a cable connected to your PC.
I'd focus on ability to organize books on the reader and the ergonomics of the device. About the 400th time you turn the page, you really start appreciating how well the reader works for you. The matrix will also show you some other nice readers that are not as well known, such as the PocketBook. Almost every type of reader has its own subforum for once you think you have it narrowed down to a few devices.
If you visit Best Buy, you can see the Kindle, Sony, and Nook all together and Borders has the Kobo. Historically, Sonys have gone down in price 4-5 months after launch.