Well, that is the trickier question. My answer: "It depends on what you want to do."
If you are into mastering data prep, than I would continue down the path of the Advanced Programming Professional and study SAS Macro, SQL, and Advanced techniques such as Hash Objects and PROC FCMP.
If you are more interested in statistic analysis, I'd head for the Statistical Business Analyst and study linear and logistic regression.
If Clinical Trials sounds like fun. There is a credential that focuses on that.
Data Science is popular too if you want to go that route. You can start out in data prep portion or the analytics side, both are important to data science realm.
All just a matter of what you like doing.