It depends. For me, the exciting part of The Annotated Erdnase is the massive quantity of references to other works with techniques similar to, evolved from, or preceding those of Erdnase. Therefore it is an excellent place to begin a journey into the whole of crooked gambling lore, literature and legerdemain. Revelations, on the other hand, is more concerned with the minutiae and application of the techniques, while also detailing some modern day additions to the "calendar of sleights". Thus, Revelations is best suited to one who wishes to become a master of The Expert at the Card Table, investigating it's subtleties thoroughly, before moving on to other works.
Having said that, for the serious gambler, probably neither are suitable except out of academic interest. If you want to learn to cheat at cards for real, you'll probably want to work out which two or three techniques will get the money in most situations you're likely to find yourself, and work on those exclusively.
