In my opinion there is no right or wrong here. You always have to chose what you like best. One cool way to find some new strumming patterns though is, to limit yourself to one short chord progression or even one chord and then challenge yourself to find a number of patterns, maybe 20, maybe 50 (from easy to hard). Also you can always find inspiration by listen carefully to the strumming patterns or rhythms your favourite artists use, as well as listening to completely new music.

To your specific question though:

You may want to look for some pattern that doesn´t feel out of places of the rhythm of the melody and your style, except you specifically want that. You should always be clear what your music should sound or feel like for the listener and build the actual musical elements around that.

I hope this helps :D

Keep the songwriting work going, everyone has music inside and just needs to find a way to free it!