This is definitely among the top questions on the osteo and step 1 boards. A little lurking in the Step one forum and some time with the search function will yield big dividends.
Off the cuff answer:
Please don't ask which is best, as there is no answer to that question - it depends on how much time you have, your learning style, etc. The books I listed seem to be among the more popular choices for each subject. This list will probably just about get you through the first two years and through Step 1 for that matter.
Although convenient, I would caution against simply buying all the review books offered by a single company, as there is often a wide range of quality among them.
It is very tempting to buy more review books than you need and end up never opening them. It is usually better to commit to learning one source fully than jumping between multiple sources. However, it is also quite easy to buy review books that are too long, too short or simply written in a style that doesn't work for you. Your time is valuable, so if a book isn't working, find a different source that does work.
With the possible exception of pharm, older editions of review books are usually fine to use.
Finally, although you may be able to get away with it at times,
do not rely solely on review books to learn the material. It is extremely important to also read full-length textbooks, attend lectures, etc.
Many board questions will not be found in review books and you will need to reach back to your first two years to answer them or not to get tripped up by a foil you've never heard of.
Good luck.
