Both have their advantages. Barbell lifts allow you to go as heavy as you like 1-4rm, obviously they can still be used for higher rep range work as well. Doing a 1rm on say the DB press isn't that productive since you spend so much energy getting them into position. I love barbells on the big movements, presses, squats, deadlifts, rows. When I get into my assistance work I like to use db's because at that point my reps are higher and I am focusing on feeling the muscle work rather than just moving as much weight as I can.