7-10 are the best, as they are most closely related to the current format of the test. No one AAMC is considered the best, because no one can accurately predict what will be on the actual test. Even 3-6 are great practice. I would disagree with the TPR guys that 7 and 8 are harder than the real thing. Most people find the actual mcat was tougher than all the AAMCs (not significantly, but slightly.) However, most people find that they are scoring around their average +/- 1, so the scale will work itself out. The best play from here on out is to take plenty of CBT's from now until test day, and learn from them. I'm in the same boat, good luck.