Books seldom go bad,  more reading material is ALWAYS better, you won't damage your brain cells with a different perspective on the same subject, the three books look at the same items from different POV's. One explains it all one the changes. There is no right and wrong BUY BOTH.
NEC hand Book 130.00
NEC                 75.00
NEC Changes    130.00
 TOTAL            260.00/36 months=7.22 a month
Cost of a not knowing PRICELESS
It drives me bonkers that electricians hem and haw over a few dollars, the number of jobs I go on and ask to see the NEC and NO ONE HAS IT, is disturbing at best.