I like both BB and DB incline bench. Why not do both? Without a doubt (in my mind) the BB is better for putting on mass. But DBs, talk about working the stablizing muscles.
In my gym the decline bench is fairly popular. I think one of the most underrated chest exercises is the good ole push-up. Ever try weighted push-ups? Have someone put a 45 or so on your back and go to failure.
I once heard that the best exercises for growth are the ones where you move your torso through space instead of just moving the extremities. Sounds weird until you realize this would mean movements like squats, hack squats, deadlifts, power cleans, chins, dips and....weighted push-ups.