All three ought to be great players.
O'Sullivan reminds me a bit of Marc Savard, but seemingly a better shot. I could see O'Sullivan being a fine #2 centre in this league, maybe even a #1 (though I don't think we'll ever compare him with Joe Sakic).
Zach Parise is a stunning player in that he's got so much heart and guts to go along with his skill. I also think people will be surprised to see how many goals he can score. He's not a playmaker, I don't think. Don't get me wrong, he can make plays, but I think he can score just as well. All-around offensive threat. I'd say he will probobly be the best of the three.
Rob Schremp - just sick talent. Flat out, unadulterated, talent. Not sure about his motivations, but there's reason to believe he could be the best of the three talent-wise.
How about a couple others to this list:
Derek Roy in Buffalo - seems to just find ways to score goals. Can't explain it all the time. I don't think he's on the same level skill-wise as these other guys, but for whatever reason, I could see him putting up similar numbers. Roy has a lot of heart.
Mikhail Yakubov - lots of folks kind of forgot about him, but I caught him playing a couple games in Chicago, and I have to say, I was impressed. He reminded me a lot of Viktor Kozlov, but he was winning a lot of battles - the particular night I saw him, he seemed to be the only Hawk who was really digging in and working in the corners. Not sure where he stacks up talent wise, but I think he is due for a breakout rookie campaign next season.
Antoine Vermette - I absolutely fell in love with this guy in the playoffs. So fast, and very underrated hands. I heard he had average hands, but that's incorrect - I saw him play a couple games for Ottawa where he displayed great mitts. Not sure about his shot though. Still, he could adapt his game to a defensive role if he doesn't make it as a scorer. His speed is just a great weapon. I like this kid a ton.