I would do:
Aho
Keller
Nylander
Dvorak
Everything I have read about Aho points to a great player. Keller is right there with him but you have to worry a little about his size even though that's as big of a concern in today's NHL. Nylander is talented but there seems to be more question marks surrounding him and his intensity. Dvorak is great too but I think offensively he is just a little behind in my eyes.
These are very tough!