Well...
The B is long range, while Ns are up-close-and-personal weapons.
Score: B 1 N 0
Ns cannot be blocked, unlike Bs.
Score: B 1 N 1
A N blocking a passed P is better than a B blocking one.
Score: B 1 N 2
Two Bs are more powerful than two Ns.
Score: B 2 N 2
Bs can only move to half the squares on a chessboard. Ns can move to any square.
Score: B 2 N 3
I perfer Bs, but Ns can also be good.
I know bishops are good in endgames and knights are good in closed games, and it all depends on the circumstances, but which do you think is better overall?