Hello Rahul.

Both the carreers  are good if we look on the basis of future demand.The important factor is that both the fields are differnt from each other. Your interest towards the field matters here the most .

SAP is for the kind of person who is somehow good in programming stuff like java language and other programming languages of Object oriented programs.

On the other hand if you have interest in information collection type jobs then digital marketing is good for you. Here you should be very clear to Statistics and deep knowledge of field and R programming. 

So, choose wisely and go with the intrested one .

Thank you.

Hope it helps.