Each of them have certain advantages over another.
Bitcointalk : Typical Geeky Bitcoin crazy crowd.Mostly online money makers and freelancers.
Facebook : All the average folks who know what bitcoin is or are starting into it.
Bitcointalk advertisements are expensive compared to facebook with a limited number of market place users.Facebook is way too cheaper but promotes to a larger crowd.
Basically bitcointalk serves the niche crowd while facebook serves anybody based on their data analytics.
Facebook look pretty useless to me , I mean the same audience that you are likely going to target is the same one that is here . I know that It's possible to target other users but they probably won't be as much as interested as the ones coming from faucets , bitcointalk or other btc services where their main objective is to make profit after the ICO.