a peach of a - a particularly excellent or desirable thing of the kind specified. informal
☞ Peach has been used since the mid 18th century as a colloquial term for an attractive young woman and more generally since the mid 19th century for anything of exceptional quality.
2012DVD Verdict Survivors are scrambling down to the basement. There, they find Mickey, the building superintendent and a real peach of a guy, who has stocked the place with goods for just this very reason.