Johnson <<< Duchene. It's not really close at all.
Duchene is a bigger, faster, stronger and more accomplished player, especially representing Team Canada which is the hardest to crack. Surrounded by inferior wingers and D, plays in the toughest division in hockey, defends against giant size forwards while trying to figure out the coaching mess the team faced the last few years.
Moving Duchene to the East and surrounded by better players and coaching, his numbers are likely to dramatically improve. So he is definitely worth more and it's not pedigree.