Weight training stimulus is best applied systemically (compound movements/multiple muscle groups) by moving a heavy weight through a range range of motion - i.e. this is what makes the squat, deadlift, powerclean etc.. so effective. The only issue with DB's is that you can't handle as much weight as a barbell. They are certainly great but will lag the barbell variation for effectiveness in the vast majority of cases. That said, they absolutely have their uses and you aren't forced to pick one (but if it were either all DB or all BB - you should absolutely go BB).