Asking which is worse, the FBI or the KGB, is rather like asking which is worse, the New York Times or Pravda?
I would argue the New York Times, because it is trusted almost to a religious extent by a large portion of the public, even though it often lies blatantly for political/ideological purposes (most recently about the death of Capitol Police Officer Brian Sicknick).
From my visits to the Soviet Union, it was clear to me almost no one believed Pravda about which they would make dark Russian jokes. (A few good ones are here.)
With the FBI and the KGB (now known as the FSB or Federal Security Service) it is much the same except, in all fairness to the FBI, they haven’t, to my knowledge, executed any of our fellow citizens or sent anyone to Siberia, although what they attempted to do, and almost succeeded in doing, to General Michael Flynn is pretty much the equivalent.
Apparently the FBI, again much like the KGB, exploits “honey traps,” or generates false rumors thereof, as Rep. Devin Nunes revealed Sunday via an FBI memo turned over so late it calls to mind the Venona Papers that finally, after decades, implicated FDR’s state department crony Alger Hiss as a Soviet spy.