Our biggest need is a #2 defenseman so try to trade one of our centres for one.
I always trade O'Reilly not because he's bad, but EA games doesn't really take in work ethic or defensive responsibility into their gameplay.
As of now ROR probably will have the greatest trade value. Don't know if you can get someone on Myers level, but try to find a two way player like Burns.
The people who are expandable for us are any defensemen, old or young, talented or depth. And centre depth. What you need to do is before you trade anybody else, try to play with majority of the players first and see which ones fit your style of play.