Finished the rewatch: I would rank the seasons in the following order:
1) Narcos Season 2 - the sheer insanity of Pablo vs. everyone and all the corners the DEA cut and deals with the devil the DEA made make this the best season.
2) Narcos: Mexico Season 2 - the emergence of the plazas as a threat to Felix Gallardo as he betrays his allies was very interesting and builds up well. Neto and Rafa were great characters.
3) Narcos Season 3 - For all their alleged class and refinement, the Cali Cartel was as vicious as any of the Narcos, especially when they got dragged into a fight with the North Valley Cartel. I really liked how sharp the DEA was but still had trouble keeping up with Cali's chess moves.
4) Narcos: Mexico Season 1 - The rise of Felix Gallardo. This season does a great job portraying Felix, who was brilliant, but not loved or even really respected. The corrupt DFS Captain was a great character.
5) Narcos: Mexico Season 3 - Sinaloa vs. Tijuana was really interesting, especially because, as Felix knew, they should have been allies but turned into vicious enemies. Juarez's Amado was very well done and believable, but like everything in Mexico, no matter how powerful a Narco got, they couldn't get beyond the corruption of the Mexican elite like Hank. Some of this season is sad and hopeless, which accurately reflects the Drug War. My only complaint was there was not much about the Gulf Cartel, which became very important in real life during the 2000's. If they had added more Gulf this season would probably have been my second favorite season. The whole season feels like something important is missing from the story. There are enough allusions to the Gulf Cartel that it almost seems like they started to film that plot arc, then edited the Gulf out.
6) Narcos Season 1 - This season is still excellent, but it is my least favorite for two reasons: 1) Pablo is a bit of a super villain in this season which, while mostly true, makes the story a bit less dramatic, and 2) the first three or four episodes are a bit slow. It covers stuff that actually happened, but Pablo's political dreams were never realistic and just aren't that interesting compared to the rest of the story.