I'd recommend books 2 though 5. Having the full set is amazing to go though, but also is an amazing reference if you are reading another book and it lists a move you've never heard of.
If you want some fun stuff, check out books by John Bannon's High Calliber or John Gustaferro's One Degree. I also love Paul Harris's Art of Astonishment set. Aaron Fisher's Paper Engine also is a great book.