I tried the Woodall's directory a couple of years ago and was very disappointed. Many of the directions to the campgrounds were wrong. One CG owner told me "I've told them again and again their directions are wrong, and they won't change them".
I have used the Good Sam/Trailer Life directory for years. The last one I got though (2014, I think) disappointed me. It seems there are an awful lot of RV parks that are not Good Sam Parks, that have no write-up in them. All they have is the name, an address, and a phone number. They don't even give the number and size of the sites. Seems there are a lot more of those than there used to be.
Having said all that, though, I still think the Good Sam/Trailer Life directory is the best available.
Ed Headington