As previously mentioned Commissions in New Jersey are negotiable. Any agent that states the "standard" is actually committing an antu-trust violation.
But to answer your question, it is not the commission amount that is the worry it's what the seller puts in their pocket after closing. A good Realtor will place all their marketing into the home to get the highest price and when that offer comes in, it is their negotiuating prowess that brings the price up even a little higher which makes up for the discount broker whose sole purpose is usually not getting the highest net for the seller, just getting it sold for the sales sake.
It is best to interview more than one agent when looking to sell your home. Thier marketing plan must be complete, the pricing strategy should be succinct and most of all, you must feel comfortable with the agent.