If I had to pick today then Keller looks like maybe the guy. His scoring has died since other clubs started hitting him but he will adapt. He gets more TOI than the other two but the Yotes can't protect him either because of their weak forwards and he is the best shooter. Hischier looks good but he wasn't nearly as dominant as Keller or Marner at the lower levels so I wouldn't place a ton of reliance on his ability to ramp up his scoring based on this modest sample. He could still be a sub 35pt player this season. Its really early to predict Keller v Marner and with his rookie season one of the better ones ever for a teenager, Marner is probably the safest bet to finish strong. Still, one of Keller or Marner could be a lot better than the other over their careers. Joe Thornton scored 41 points at age 19 and Jeff Skinner had 63pts at 18. At 21-22 it will probably be a lot clearer