I have two favs (not surprisingly!)

The German Shepherd - one of the most versatile working dogs we have. They are used as herding dogs, police dogs, search and rescue dogs, guide dogs, army dogs, protection dogs, security dogs ... the list is almost endless.
The Border Collie - one of the truest and least touched working dogs there is in this country (and probably the world) today. There is no better livestock dog than a border collie. Their great intelligence can also be adapted for use as sniffer dogs for the police and search and rescue dogs on the mountains and hillsides of the UK.