Burger King are much better on Twitter and have a nice level of engagement through their retweets. They have fun tweets too.
They also change their message a little on Twitter so they are not duplicating the same text as on Facebook
This type of fun attitude should be applied to replies on FB as Twitter is much more transitory but people tend to open and read FB comments more.
Twitter has a link on their homepage to their email newsletter, which is great for email capture and consequent email marketing.
Facebook has a similar link but it is hidden in it’s About Page.