These are the teams and players I usually look to trade for:
MLB: Chicago Cubs. I collect team sets and the inserts/parallels. As for Autos/relics and low numbered stuff, I just pick up what I can.
NBA: Jordan, Marbury, Kobe, Iverson, Durant, Westbrook, Shaq, KG, V. Carter, D-Will, Raja Bell, Utah Jazz and cool cards of random star players/HOFers
NFL: Randy Moss, Adrian Peterson and the Minnesota Vikings.
I also collect star player/HOF RC's across the 3 sports I collect, especially Topps Chrome.
I am always looking to trade for anything I don't have of the above mentioned players/teams. I can also sell if you're interested in anything.
Link to my Sportscardalbum for some, but not all pictures of trade bait and my own collection: https://sportscardalbum.com/u/cublife