My Prediction
Although the polls seemed to be tightening somewhat, the latest two polls show Booker with a 14 and 22 point lead respectively. It looks like he is going to win by a large margin.
The question is how big. RCP has Booker's average lead at 14 points. Democrats usually end up doing better in New Jersey than their polls suggest, so it could be well over that. OTOH, the election is on a Wednesday in October, which could depress votes.
My prediction is that Booker will win by 14 points, as RCP suggests.