<p>I don't know about the Barron's GRE list, but I've studied the 3500 one, Sparknotes' 1000, and am halfway through Testmasters' 2200(2006 edt). </p>
<p>You'll see rare words like bard, arroyo or nabob in each of the "big" lists. Though these words may rarely appear in a sentence-completion question, they might appear in the passages. </p>
<p>The 3500 list is awesome. Granted, like most lists it is somewhat limited in connotations, but it is wonderful because it has sample sentences unlike Testmasters' or probably Gruber's(not sure about the latter); however, you should also keep up with the recently published lists and with the mini-wordlists that CCers have compiled after taking the tests.</p>
<p>In my sense, you had better continue memorizing Gruber's or start TM's if you cannot find Barron's 3500. And, don't forget to look for alternative meanings to the ones that the list provides.</p>