Depends what your goals are. If you're looking for increases in endurance, muscular speed and strength, better recovery, dense muscle growth, and enhanced libido, then you would go for Drive. If you want better pumps, vascularity, focus, explosive energy with NO jitters, and are looking at gaining some mass whilst losing BF, then you would go with RPM. Drive is a non-stimulant, whilst RPM is a stimulant. However, both RPM and Drive stack well together, especially of you are looking to cut, or gain definition. It also works exceptionally well as a performance stack.