Honestly I mostly enjoy the people he goes out and films.... in Where to Invade Next, hearing the perspectives of people in other countries on various important issues like education, healthcare, gender equality, worker's rights/benefits, justice systems, etc.... that was interesting.
Moore's perspective is obviously "They are doing it right/better, we are doing it wrong"... in some cases I agree, in others I disagree or I think there is nuance/grey area he is ignoring... but the content he gives you is interesting IMO whether you agree with his ideas/conclusions or not.
I will say this, in most documentaries I watch, I feel you often get 1 perspective on an issue.... I do enjoy it more when they manage to get both sides of a proverbially story.
Inside Job did this the most IMO, they tried to get every Wall Street person involved in the financial crisis to tell their side, and most of them refused. If you refuse to present your side of an argument/story, you concede it to the perspective of the other side.... and with the Wall Street crooks probably rightfully so.