Tough call. It's between Darvish and Crawford to me. I think I would go with Darvish. I don't think you'd get a better player than Darvish back if you drafted Konerko and traded him, and he'll probably start declining very soon.. If Crawford comes back healthy and tears it up you could probably trade him for a better SP than Darvish... Crawford is very intriguing as a keeper and has the highest upside so I wouldn't blame you for picking him since the team isn't contending this year.
Gun to my head? Darvish
Here's the pitch on the way, a swing and a belt! Left field! Way back! BLUE JAYS WIN!
Darvish if he is willing to take risk and looking for someone for 13 not for trading this year
Crawford otherwise as the most conservative option, he will net the most on a trade this season of these options
Personally league sounds like they need some rule adjustments with that much quality being kept League rules should be designed to benefit teams near the bottom of the standings