Well, I think this is an hard question...

About the JB 4.1.1, the stock 1.05 rom is surely very stable, without any battery problems.  If you want to have root access and forget about Chinese apps, the Kasty or the Stassen versions are the best (search the forum..).

About the JB 4.2.2, hmm, my feeling is that every single appliance of cube has its own best rom.  I mean, my u30gt2 found the best compromise with performances and battery drain with the 2.04 test4 2013-08-07, but a lot of people reported good feedback with 2.04 final or with 2.03.  Up to you to choose among the stock and the Kasty and Stassen versions (again, search the forum..).

Give them all a try and get the best for your cube.  Not a final recipe, but I think that if you decided to buy this tablet, well you had the willing to test and expertise this nice toy...