Seeing the movie Two Lives brought that home. We now know a lot about what evil things various Soviet Bloc secret police agencies did, for the simple reason that the regimes they served vanished, and the replacement regimes have not been interested in preserving the secrets of their predecessors.
So far as the misdeeds of various Western secret police agencies (and, be honest now, that’s what they are: secret police don’t stop being secret police just because they serve ideologically convenient regimes), we don’t know vastly more than we did at the height of the Cold War. Sure, there’s been a leak or two here and there, but no vast revelations on the scale of the Stasi archives falling into the hands of its opponents.
Any attempts to document said misdeeds will therefore be biased towards making the Soviet side look bad (not that that’s particularly hard to do). Circumstances dictate it: there’s just not much factual material to work with when it comes to the Western side. It cannot really be otherwise until, say, the MI6 archives suffer a fate corresponding to the one the Stasi archives suffered.
All we can do is guess, based on the observed overt behavior of both sides’ governments. In brief that guess is “the Western intelligence agencies were less evil than their Soviet Bloc counterparts, but they were still plenty evil.” The USA, after all, backed some thoroughly vile Third World regimes, even though its record in Europe is indeed much better than the Soviet Union’s. In other words, better overall, but still plenty evil.