In the area we live & hunt, I consider a 315+ bull a big bull, there's just not many of them taken. Anything in the P&Y size is defenitely respectable as Archer18 mentions.
If I were hunting in a more elite area then the size would very as to what I felt was a big bull.
In a trophy type area I would consider anything in the 340ish-+ a real trophy with a bow!! I would have it mounted! To date my son or I have never had a bull mounted. So on goes the search for that elusive trophy.
Actually we're not trophy hunters, we usually take the first branch antlered bull, as there's others in our camp to consider as they also want to fill their tags! ElkNut1