From a folksinger's point of view, Philadelphia has more paying venues than any other town I have been to, and I have lived in Dublin, Tel Aviv, New York, Boston and Los Angeles. (And this is before I knew about Big Mick's Celtic sessions in nearby Berlin, N.J.) There are, literally, dozens and dozens of professional folk performers earning a living in the tri-state area around Philly.
Philadelphia is the center of many folkmmusic events and genres. Banjoists come from everywhere to hear the annual Mummers Day parade with its scores of string bands. Philadelphia is one of the major centers of Black Gospel choir singing and one can find at least one concert every Sunday. Ethnic festivals and bazaars are everywhere. There are thriving Puerto Rican, Irish, German, Scottish, Jewish and Italian culture societies, each with a full program of music and dance. The Philadelphia Folksong Society is the nation's largest and best funded. The Philadelphia Folk Festival just held its 45th successful weekend.
For a folksinger, Dublin is heaven but Philadelphia is parnessa.

                         Mike