Here is my reasoning for Seguin:
1. He actually plays in the NHL. One of the few cases where Schenn doesnt get the "centre depth" excuse. Both players had to impress mightily to stay on their teams rosters. One did, one didnt. I realize Seguin's draft pedigree helped a bit, but he earned his spot in the NHL.
2. Seguin is putting up very good points as an 18 year old. Could hit 30 the way hes played lately, and expect his point totals to increase A LOT when he gets more than 10 minutes of ice.
3. Seguin does most things better than Schenn. Hes a lot faster, slightly better passer, and has a better shot (has a good release). Schenn has physical play, and defensive play, but thats it
4. Schenn's footspeed will prevent him from being a gamebreaker like Seguin. This was shown at the WJC, when he was unable to will his way through team Russia, like Kuznetsov did.
All in all, Seguin will likely end up a better player. I am not thrashing Schenn at all though. For if neither were to become offensive beasts, Schenn would be able to play a 3rd line role more effectively than Seguin. Schenn will be a very good NHL player, and is elite in his own right, but Seguin just has that quality which stars have