Which Design Pattern to use in multi file output situation?

I have a problem in hand where I have to generate multiple type of file output like PDF, Excel, Text file etc. with the data depending on the user input.

I am trying to implement a Design Pattern that will help me to get rid of the design flaws and make me future proof if some new file output type come into picture.

I have zeroed in to Factory and Strategy Patterns but unable to decide between the two.

Kindly suggest which one to pick in the situation explained above and why? Also if any other Design Pattern can also be implemented over here?