Get the ‘17. It is what you will tested on. Go to the pretest class. You need to know something of State Law.
Where is the other post?
I had same question - where is other post.
Also agree '17 is what will apply to test. Things like raceway fill and conductor ampacity you can use most any year of NEC, little has changed with those kinds of things and bulk of questions may very well be ones that can be answered by most any year, but there is likely to be some that will need the '17 to find correct answer.
Used to be permitted to take a copy of state electrical act to testing, probably still is. There will be questions on state laws.