I used the version published in like 2004 I believe and it was plenty of info. I'm not sure if any new info has been added since then, but I did not see an immuno question on my test that wasn't covered and I felt like my test had a good bit of immuno on it including ILs and CD markers. The Lange book was a very good read IMO. I would say any edition you get your hands on 2004 or newer will be fine.
Basic Immunology, by Abbas (and Lichtman) is a terrific text. The whole book is fairly concise (we used it for class), but the diagrams in particular are excellent, and the book can make for a reasonably good review for Step 1.
I used Abbas and Lichtman in class and picked it up a few times for reference while studying for boards. I read lange for boards (just the immuno section) and I was not that impressed. UW had most/all the important stuff in my opinion but it isn't that long, so in that way it's good. I just felt that not all the info was high yield.