I used Peterson's a while ago (for 2-3 months). I found it quite resourceful since it contained a large number of vocabulary and they are well-organized in categories. These vocabulary were in general close to what you may see on the real test. I think around 3,000 different words were provided in Peterson's. Of course you may encounter an overwhelming feeling by these 3,000 words. However, divide them into segments and you can find it less complex. Overall, Peterson's seems to be a worthwhile resource, I recommend you to refer to it.