Hickory provides a strong but mellow smoke flavour and is considered to be great on any meat but is particularly great on red meats and pork. 
Apple is a sweeter smoke and is traditionally used to smoke white to pink meats like fish, chicken and pork. 
Mesquite provides a slightly sharper/stronger smoke flavour and is considered to be great on any meat, and like Hickory, is particularly great on red meats and pork. 
Outback Campfire has a very mellow smoke flavour with an added highlight of caramel that gives it the added ability to provide a slight warm brown coloured glaze to the surface of your meats making it very useful as a browning agent as well as providing a char grilled campfire flavour. You can spray it on your roasts prior to and during cooking, particularly good for roast chickens and for a fantastic unique finish to pork crackling. Outback Campfire also gives sausages and salamis a great rich colour and smokey flavour.