It is highly recommended to start off with this upper chest
exercise because the upper chest is often neglected in most people when it comes to hypertrophy (muscle growth) training.
Benefit 1: Allows greater range of motion for pecs
- More hypertrophy. Range of motion is indeed a key factor when it comes to maximising muscle growth as proven in studies here
Benefit 2: The Incline Dumbbell Bench Press has also been proven to be the best chest exercise at activating the upper chest
by a study by Bret Contreras here
Benefit 3: Last but not least, using dumbbells would prevent muscle imbalance
since each side of the chest is trained with an equal amount of weight using dumbbells
In terms of the angle of the incline bench, you should aim for between 30 degrees to 45 degrees to minimise the front delts being activated and maximising the upper chest activation. Try out a few sets for each angle to test your preference.