Hi Teyrnon and welcome to MR!
I got my sony 505 earlier this year partly because I was having space issues and I'm delighted. I've been reading much more, and I've actually managed to reduce the number of paper books I have in the house because I've replaced old paperback versions of classics with ebooks - mostly downloaded from here.
Whatever you choose there will be free books available - as well as the books here there is the
wiki which has information about readers as well as book sources.
As I'm in the UK I didn't get a kindle because I couldn't use the Whispernet, but judging by the forums here there are lots of happy users, and the same goes for the jetbook. I think that whatever you get will be a benefit to you, and they're all good for slightly different reasons so it depends what's most important to you.
I have to say I love my 505, and have no regrets about getting it. If you're in the US, you can also easily use it to borrow library books, which is a good way to read more recent releases without having to pay a large amount of money for them. The wiki has more information about borrowing ebooks from libraries as well
If you have any questions just ask - people are friendly and helpful here!