In theory personalized would be better. In practice I have seen several ads targeted just based on "living in large geographical area" and is "any gender aged 1

In theory personalized would be better. In practice I have seen several ads targeted just based on "living in large geographical area" and is "any gender aged 15 to 50". The ones that were personalized where insulting. Like Facebook showing me ads for healing stones when I have my religion marked as atheists. Facebook needs a lot less data and to force their adbuyers to actually target their ads. Probably though they don't because then the ad buyers will find out how little they actually gain from the ads.