You probably want Berkeley Review. Their chemistry books in particular blow away the rest of the competition in my opinion. The main asset is the loads and loads of MCAT-style passages at the end of each section (roughly enough for 100 questions at the end of each passage!!). If you're a proponent of learning by doing, get these books. You may as well get these if you're starting ahead of time, since it'll take you time to get through the problems.
EK ain't bad either, if all you need to do is a quick review. They are relatively concise while Berkeley Review is more detailed. So they're really useful if you already have a good understanding of the concepts and just need a refresher. You may like one or the other, or both. In my opinion, they are good for Biology in particular since I think most people hate having to go through an entire Bible of Biology facts.
You could also consider buying the in-class books for Kaplan or Princeton Review from people who have already taken the class. You might find them useful. One book I suggest in particular (really, the only one) is the TPR science workbook. Craploads of problems, though they're not as high-grade as the ones Berkeley Review gives you. Good for working on weaknesses as you diagnose them.
Bottom line, as long as you don't use something relatively low-grade like Barron's (it has worked for a few people, but in general it doesn't get favorable ratings), and you put in the time (hundreds of hours probably), you will get a good score. From there, the rest is up to you.