17. Bd2 or Bd3. One reason for this is because two of your big advantages are space and activity.
If you trade pieces off, your opponent doesn't mind less space, because he has no pieces that are restricted by it.
If you trade your active pieces for his bad ones, you will lose some of your advantage. Whenever you trade, think to yourself "which piece is better?"
I had a time and space advantage in the middlegame, but foolishly traded into an endgame, thinking I would have a superior endgame position. I didn't. I would like to know how I could have capitalized on my position before I swapped pieces
, and whether there was something different I should have done in the endgame.