As you've read in this thread, taking a course is different for everyone. For me personally, I couldn't have done well without my course. My course had great teaching, gave a bunch of mnemonics and tricks that I have never seen anywhere else. I think because they only do MCAT, they do it differently (better) than the big companies. But everyone is different. If you can study on your own and have good test taking skills, then maybe you can study on your own.
I would strongly recommend the following books and exams:
Gen Chem: BR and nothing else--it's absolute gold.
Physics: BR for text and passages. PR had some good passages too
Biology: EK for text and a combination of EK for 1001 questions and BR for passages
Organic: NO text because it's not tested enough to make the time worthwhile and BR passages
VR: EK text and passages from anywhere you can get them (EK, BR, TPR, and K)
Exams: AAMC 5, 7, 8, and 9, BR 1, 2, 4, 6, 8, and 9, K 6 and 8 (I think) and all of the BR review exams. I hear K has very good review exams too.
If you choose to take a course, I'd strongly suggest BR. Their teaching is great and the handouts that come with the class (probably about a thousand pages of review, tricks, and passages) are the very best materials of everything I used (BR books, EK books, and PR books).