the "esf" is a very good "non profit" look, being also in social work myself...many of the organizations get anagrammed...such as esf, ymca, fbi, nypd etc.
I like the layout and boldness of #10. Our main focus though is our service-oriented activities, so we don't want to lead with a capital building for our emblem. Also, we can't use E.S.F as it is already trade-marked by a series of kids summer camps.