The Kaplan books go the most in detail while ExamKrackers focuses more on the main subjects that will be tested. The ExamKrakers books require having some basic knowledge in the subjects before diving into the books. However, I would recommend not spending too much time on content review and more time doing practice questions and practice tests. Uworld is a really good resource for practice questions and explanations on the practice questions.
Towards the end of studying for the MCAT, it is crucial to focus on the AAMC practice materials and practice tests as they are most representative of the real test.
However, I know these resources are a financial investment. A free alternative is Khan Academy. Additionally, some websites offer 1 free practice test each (for instance NextStep).
Best of luck!