The older Burgess units were built like tanks. The newer models have more plastic parts and aren't that different from the Black Flag Foggers. The Black Flag is easy to use, well balanced, and is designed to take the shorter propane tanks. Its only draw back for me is the fogger tank is part of the body/unit. The Burgess fogger tank screws off.
So if I were buying a new one, I would probably get the Black Flag. Its easy to use, one just has to be more careful when filling it. When I was taking the Burgess back and forth, it was nice to take the fogger tank off and pour the insecticide back into the bottle, wipe the tank down, and have a clean unit to put in the car. You try pouring the insecticide back into a bottle with the Black Flag and the fogger and bottle are going to be a mess. For stay at home use, this does not need to be done so its a non issue.