This comes down to a deep and old argument, can you put anything before blood? Is an adopted parent equal to a biological one? Is there something to say about imprinting vs a natural attachment/bond? From what we're shown, I have to say, he loves Richard more, and has more reason to be attached to him. However, since Bruce is really his dad, if he had to pick one, he may very well do what a lot of real world kids with bad fathers would do, pick their real father.
it's different, Dick is like a brother and Bruce is his dad
For now he can connect more with Dick (or could, cause he dead) but later on he would grow into the love of the father, as usual
but yeah, for now, Damian loves Dick more than Bruce