I would like to quote this from TechWyse Blog, an internet marketing company in Canada - "Google gives Plus users serious search engine juice, helping you reach higher into the coveted first page on Big G".
Like any other business or relationship, it takes time to beat the 2 billion users of FB. Google is already claiming to have surpassed 200 million + users.
I would still stick to the quote above. FB Likes may not be a valid sign of user engagement considering that updates appear in a users page only based on its popularity.
Way to go for G+ for all the good reasons.