Booker is Newark Mayor Cory Booker. I think he probably has the greatest name recognition of the potential candidates. He's too accepting of Charter Schools for my tastes, but I like many of his other views and find myself in agreement with him when he's been on Bill Maher's show, for example.
Sweeney I personally don't trust. He's too conservative for my taste and too willing to go against the unions and cut deals with Chris Christie.
Sheila Oliver I'm not familiar with, although having a black woman in the Senate would be nice; we need more women and minorities represented.
Likewise, I'm not familiar yet with Frank Pallone, but I'll be educating myself in the coming months.
Haven't heard any news of possible Republican hopefuls for the seat in 2014, but any Republican would be a long-shot to getting elected in NJ anyway.
It would be interesting if Barbara Buono decided to run; she's challenging Christie for Governor of NJ, but in the event she doesn't win, it's possible she might get in the senate race.