Bishops have more range, but knights can trap pieces in ways that others aren't able to. I've always struggled with what I'd rather surrender first. Tough call, I think.
I agree Chuck although I’d say all knights early since they aren’t deterred as much by pawn structure. Also seems like a lot of other factors come in to play like experience of the player and opponents. It’s harder to see the board in regards to knights when you first start playing. Easy to underestimate their sneakiness.