Corn fed, free range and hormone free chicken is the way to go.
I normally get a 13 to 15 at Powerhouse market (@$10) but they are available at good butcher shop. Boy am I glad they are being stocked (chilled) at Superior Meats, Holland Park. After tasting sausages from various butchers, I find the Irish sausages at Superior Meats best suited my palate, Bangalow pork sausages are also very good.
959 Logan Rd
The butcher shop has recently expanded and now include a seafood counter.