Just take biochemistry. There's too much of it in the test to half-ass the content. If you are a non-trad or don't have access to it, I would suggest using the AAMC checklist (available from the AAMC Official MCAT 2015 Guide) for every section in conjunction with a good introductory biochemistry text (we used Matthews 4th E at my Uni, "Biochemistry"), Khan Academy, and / or Berkeley Review biology to make sure you understand every single bullet point on the checklist relating to biochemistry.
Particularly, you should understand how to read data produced from common biochemistry techniques including purification, immunoassays, spectroscopy, binding assays and kinematics, kinetic and thermodynamic control, enzymatic inhibition, cloning and gene knockouts. Data interpretation is key on the exam.
Lastly go to the MCAT forum on these boards and read people's study guides for other opinions / perspectives that might be more suitable for you if you don't like my advice