In terms of better player, the Nets have him, no question about it. Williams is a floor leader, who can defend. Anthony is a scorer, who takes off on defense and hasn't shown the ability to make his teammates better. The question must be begged, if Deron Williams was on the block (after that episode leading to Jerry Sloan's resignation), why weren't the Knicks on him? If Walsh was a sleep at the wheel, then he should leave when it's all said and done, since he should know better (especially with Mike D'Antoni coaching) that the PG is more important. If not, then it's pretty typical of Dolan to not have his eye on the prize. I'd take Williams over Anthony in a heartbeat.
However, the Nets still aren't guaranteed nothing with Williams. He would need to sign an extension in order for this trade to be a success, and add another star to join him. If that happens, the Nets are in better shape than the Knicks assuming Dwight Howard joins Williams, even if Chris Paul goes to the Knicks. And if I'm Paul, why would I go to the Eastern Conference when the East now has Williams with Derrick Rose, Rajon Rondo and John Wall. He would have an old Steve Nash and Tony Parker as his lone PG competition.
To sum up, the Knicks got the guy everyone assumed they would get. The Nets got the better guy no one thought they'd get.