If I were you, I would use Facebook multi-poster after targeting the right groups.
Either that or use a tool finding and targeting the right groups.
Group targeting is crucial here because you are trying to get people who are broadly interested in your content to eventually become members of your page.
There are two ways to play this game.
You can share direct content links on Facebook.
This can get quite a bit of direct traffic, but the loyalty probably won't be there.
The better approach would be to create a Facebook page and promote that to related Facebook groups.
The key here is to publish very specific content on your page and then, share that content.
If you play this right, you would be able to get highly filtered traffic and you build two assets at the same time.
First, you build your main website's traffic.
Second, you also build a nice niche-targeted Facebook page which you can then use to either promote your other websites or even promote content that has affiliate links.
