Hi Rebecca. Welcome to MR!
I agree with ruth1304 that you'll probably be happy either way--because you'll be
reading! On an e-ink screen!!
I've said in other threads that I think you get more bang for the buck with the 505, but there are a couple of things I really like about my Kindle. One is whispernet connectivity to Wikipedia. For example, I'm reading
A Tale of Two Cities and it's neat to be able to look up some of the characters to see if they were real historical figures and if so, what part they played in the French revolution. I do that kinda thing pretty often. But I'm probably one of Amazon's worst customers; I get most of my books from right here on MR