Social bakers just released a study that showed the engagement ratios of communities of ten large brands active on social media marketing. The article concludes that Facebook is a better place to engage fans due to the intrinsically richer communication it enables and the ease with which social interaction occurs.
It seems that brands that have high Twitter engagement have specific twitter-centric campaigns based on content that is frequently updated. Facebook engagement seems more accessible to brands as it can be sustained by a combination of bespoke Facebook actions supported by standard marketing resources like images, videos and websites.
Do you focus on Twitter or Facebook? What do you see as the role of each of these two media?