Hamburger- small amount of hickory, oak or mesquite.
Steak- same as hamburger.
Chicken-small amount of apple or cherry. Chicken is very easy to oversmoke.
Brats- small amount of apple or cherry.
Pork-ribs I prefer apple or cherry. Or small amount of pecan.
loins or tenderloins same as ribs.
butts I use pecan or a mix of approximately 1/3 hickory
mixed with 2/3 cherry or apple.
Oak is used by a lot of the BBQ joints in Texas because it's plentiful and makes a very good bed of coals. It's very good for briskets and chuck rolls.
Never use green hardwoods like oak or hickory for smoking, for the same reason they aren't used in fireplaces or woodstoves. They don't combust efficiently and will produce a lot of creosote and soot that will make the food bitter. Green fruit woods are OK. Mike Mills, of the Apple City Smokers, won many awards using nothing but green apple wood. Peach, bradford pear or any pear tree, apricot, sugar maple, apple and cherry are all good for smoking with because they tend to be mild.A friend of mine uses peach wood almost exclusively and his ribs and chicken come out great.