Wow! I expected to get a "it doesn't matter, they are the same" sort of answer and a very short thread.
Thanks for all the responses!
I'm going to stick with Kobo for now. I haven't been unhappy with them, except for no longer having a web reader and their desktop app doesn't work on my work computer. (I can't really try to troubleshoot it when I'm not supposed to install my own software.) It's just for lunch and it's not a big deal to have to plan ahead for my next book.