The consensus is that a bench set to an incline of 30 to 45 degrees will target your upper chest the best. Anything lower than that and you will start using more of your middle/lower chest. Anything higher and you will be placing more stress on your shoulders. To get the best angle for incline bench suitable for your body levers, you will have to do some experimenting. The angle that works for you might not work for your training partner.