That is a loaded question. In some cases a filler should not be used at all especially if the jowl severity is anything more than slight. I suggest you resubmit the question with a photo because then you will elicit more specific responses that you can then use in making a decision of what to do.
The best treatment for jowls is a facelift. Yes, a filler can camouflage mild jowls but in the end, you are better off with a facelift.