Which Copart broker offers the most advantages for regular buyers?

I'm planning to start buying more vehicles from Copart, but there are quite a few brokers out there and it's hard to tell what actually makes one better than another.

Besides getting access to the auctions, what features have been the most useful for you? Lower fees, shipping help, customer support, fee calculators, something else?

I'd love to hear which broker you've had the best experience with and why.