To tell you the truth, the best ones, atleast from my perspective, were the AAMC tests. They are authentic and really do prepare you for what you can expect. I found the kaplan and columbia questions to be the worse case scenario types, which meant that they were OK, but you also need to be prepared for the mediocre questions. The silver bullet and the gold standard are two books that I found to be extremely good. They are very similar to what is found on the exams. Though I didn't buy the GOld Standard, I would recommend it. Also reading is very important for the verbal section. I think both of them are by Petersons. I found it on amazaon.com, so they are easily available. To tell you the truth, the main reason i did poorly the first time was just laziness. I think that continuous practise with the material and a consistent reading habits are the best way to prepare for the mcat. Hope it helps.