I may be biased, but I think there is one main reason the PMBOK is better than PRINCE2, and it lies on their difference. PRINCE2 is a prescriptive methodology. As a prescriptive methodology, there is a one-size fits all projects assumption.
On the other hand, the PMBOK Guide represents process and best practices, and is not prescriptive. You can use this information to tailor and scale the process as required. So whether you are running a traditional waterfall project or an Agile project, there are elements which can be applied to help the project succeed.
In short, the PMBOK Guide relies more on the professional judgment of the Project Manager.