I liked 4, it’s very much a victim of being a Ubisoft game though, as in it’s more of the same. I’d say the only difference is the setting.

5 is similarly pretty good, I feel like it removed a lot of the “Guerrilla Warfare” feel of the combat but the villain is really good and the setting is pretty solid too. I haven’t played 6 though. If I had to guess though it’s the same. More of the same.