Dan, freight is too complex to generalize about and must be looked at on a case by case basis.
However there was a post last evening that was a pretty good guide.
I've never had good luck with brokers unless they generated all the invoices. There are a number of cases I'm aware of where brokers have shut down and reopened under a new name. On the other hand I've had good luck with long term haulers.
You might want to develope a relationship with one of a number of factors who specialize in this market. The costs are low and many offer additional services such a fuel cards.
Bob