Well, I don't know anything about DCnu Flash, but if he has the same power-set as Pre-Crisis Wally, then just on powers alone, he trumps Iceman. That's just theoretical though before you take into account how a Flash acts against ice-powers (Captain Cold, etc.).
Theoretically, Flash has no upper limit to kinetic energy whereas Iceman can only go as low as absolute zero. Furthermore, Flash's ability can also theoretically allow him to trump Iceman at his own game. The Wally West Flash has shown on occasion to basically stop time, and he has stolen speed on high scales before. Stealing speed, or taking away kinetic energy is basically what Iceman does. When you also factor in the reaction time of a Flash, then this is completely in a Flash's favor.
That said, if a Flash ever used his power-set correctly 100%, there'd be no competition. Considering Captain Cold can give a Flash a hard time, then a much more maxed version ice character w/ greater diversity and creativity in power-usage should have an advantage.