Both have their own pros and cons but I would like to advocate PPC (google ads) over Facebook ads.
A normal user would usually prefer using a search engine for searching rather than using facebook. First thing that clicks one’s mind is Google and hence PPC ads will generate relevant traffic.
On the other hand, How often do you click a facebook ad?
Google Ads are
-Keyword triggered
-Target wider audience
-Covers more niches
-Creates more clicks
Facebook is more dedicated to content and less to ads. Ads in facebook
-Target only particular niches
-Create less clicks
-Are not keyword triggered