One of the best exercises to build upper body strength is no doubt the dumbbell bench press. Advanced weight lifters mainly use this exercise as a testament of stabilization strength. If you don't believe me that it's counted as a stabilization exercise, you should try imagining yourself holding two 140lb dumbbells in each hand!
Not only does it require high stabilization levels, but it also requires great arm strength. Using this exercise can provide many benefits such as: increased strength levels, better flexibility, higher stabilization levels, and can also bust through some of your plateaus that you're currently stuck on. It can also hit more muscle fibers in the chest area due to the deeper lowering of the dumbbells. You can't hit as many chest muscle fibers with the barbell. So that's another reason why the dumbbell bench press is also an excellent choice of exercise.
How to do this exercise? If you're new to using dumbbells on a flat bench, then you should follow these directions especially. Lay flat on your back with two dumbbells in each hand. When you set yourself up, position the dumbbell just a little outside of shoulder width apart. Keep your back flat on the bench, elbows tucked in (not flared out), feet planted flat on the ground, knees pointed straight as the same direction as the tows. When you have all these in check, follow through with the pushing part. So push up at a decent speed. Don't be sloppy with it. When you perform this exercise with bad form, you are prone to injury.