Search anywhere on the net... but book DIRECTLY with the Airline! I use Scotts Cheap Flights, Jack's Flight Club, Hopper, Hipmunk, and Skyscanner to search and follow flight prices, but once I do find a deal, I reach out to the airline.
One thing that became very clear during the initial COVID cancellations was that 3rd-party vendors sell tickets, they don't provide full ticketing services. Getting them to answer their 800# was impossible in March & April. Often, If you called the airline to try and get a refund/voucher, attempting to bypass the 3rd-party vendor, the airlines would say, "You will need to speak with the purchasing authority regarding this ticket." In light of the current shaky situation, I'd recommend booking direct.
One exception would be the relationship bogiesan has with a travel agent. Some agents, especially those who specialize in air, ARE experts in this field. And they're worth their weight in gold when something goes bump - like a canceled COVID flight and getting a refund. Many travel agencies have an Air Team that supports the agents, and that's a good option also. Granted, if you're buying economy class tickets, you'll probably pay the same cost as the web price + their fee.... but if you're flying business class, they're often able to get some lower-than-web prices (airlines have more margin on the Business Class, so they're willing to discount to bulk purchasers - like an Air Team or an Air Specialist).
These agents will coordinate flights, seats, apply FF#'s, handle special food requirements, make the special assistance arrangements, luggage issues, apply TSA and GE #s, etc. That's what the fee is for. But the real value of the fee is if something goes bump because they have contacts and phone numbers the average traveler cannot access.