Best depends on your freight
Which broker is best depends on the freight in front of you, not on a ranking.
Most lists of top freight brokers rank companies by revenue. Revenue shows size, not whether a broker handles your kind of freight well. A broker built for steady truckload lanes may struggle with a Sprinter van load booked at midnight. A broker that excels at urgent freight may not be the cheapest choice for flexible pallets.
So start with your own freight: its size, the mode, how urgent it is and how often it moves. The best broker for you is the one that fits those answers and proves it is legitimate.