i would also go with q-bank...i am actually taking the usmle tomorrow, so i don't know first hand what is more like the test. but, the q-bank was a bit more informative for me, and a bit easier to use. medrevu seemed to be a bit more difficult, but it didn't feel like the exam. or at least like the NBME practice tests. if you have more than a month or so, you may want to get both. if you can only get one, i would go with q-bank.
good luck!