The show is undoubtedly an indictment of the war on drugs and calls it a wholesale failure, no question there. It condemns the violence on the streets and is honest about how violent the police are. And it is completely consistent on the theme that people turn to crime because the socio-economic system left them no other option. As the show spirals out into other fields, it shows how thorough the corruption of the whole government and how impossible it is to change anything. Anyone who actually tries reform either gets boxed out of the process (Bunny Coleman, Daniels) or conforms to the corrupt system (Littlefinger).

But while it condemns the war on drugs, there is still an element of "the police could be saved through reform." Especially season 5 which is the worst season for a lot of reasons. The case against copaganda is much stronger without McNulty's bullshit fake serial killer plot, in universe it confirms that with better allocated resources police can solve stuff like murders. Season 5 was saved by Marlo's crew and the Newspaper storyline.

I think the biggest argument against it being copaganda is that you always follow the people they're investigating. They are main characters as much as the cops (and are usually much more compelling characters). In every season at least one of the criminal characters chooses to reject the violence of the drug trade in some way. I don't know of any other "cop show" that actually gives a shit about the people on the other end of the table, especially not to the extent we see in season 4. Season 4 is the highmark for showing the school to prison pipeline and actually trying to offer an alternative.

And as for the police, we see at least two characters who go through the journey of "don't be a fucking cop anymore, it's awful." Prezbo is actually pretty based for killing a cop and then becoming a public school teacher.

I'm not making an argument either way I just wanna hear your thoughts.