said 1 year, 1 month ago:
Not sure if your campaign will lead anyone to your business URL, but if it does, I’d suggest also doing some analysis from Google Analytics for your site to see if people are coming to the site after engaging on Facebook.
From your description if engagement is your top criteria, I’d suggest “People Talking about this” and “Engaged Users” per post. That also can help you see which posts topics are most engaging and also test with timing of posts to see when people are most talkative. One of my favorite and simplest numbers that I enjoy is the “shares” on each individual post in the timeline.
Wish you the best on your campaign.