A Dover set can be got quite cheaply on eBay nowadays. My set is invaluable and I couldn't do without it. Having said that if I was starting out afresh I would want a Loomis set as all of the appendixes/addenda have been placed with the appropriate ballads now which is very useful. If you're after just the traditional ballads to sing I would strongly recommend the wonderful reprint of Bronson. Child is very useful for texts and background info, but you only get the traditional ballads in Bronson that have tunes. A lot of the material in Child has never seen oral tradition or has been cobbled together by poets. Bronson by and large (unintentionally) weeds these out. There is little or no evidence to suggest for instance that the 40+ Robin Hood ballads were ever part of an oral tradition. They were almost all written for the garland press and whilst they all have designated tunes the only ones found in oral tradition are those few that were reprinted in the 19th century on cheap broadsides.