If I had to analyze the options:

• YouTube: it's full of ad blocker on you place the ads there, or people just know influencers shill shit stuff just cause they get paid, also the crowd will be limited

• Facebook: it's less common among youngsters, lot of trolls and dumb people but it's extremely spreaded and very used

• reddit: users are generally not very crypto friendly, they have high expectations and standards, not a good target for ads

I'll pick Facebook, but if I could I would add Instagram and vote for it, that's where lot of people are pushing towards, youths included