Telecom Broker Yes, No Maybe?

First, the context: I've been doing networking for a long time... CCNP, operated a number of networks, etc. I've brokered some telecom services as well over the years but never made it my main thing, but have thought about it...

More generally do you prefer to work direct with providers or with telecom brokers for WAN solutions, fiber, datacenter leases, SIP trunking, etc or do you prefer to leverage an agent to vet multiple solutions, negotiate pricing and so on? Anyone who has worked with a broker/ agent in the past what are some other things that really added value and made it worth wile?

Thanks!