Woad King Darius is the best and subsequently the most underrated Darius skin.
Nobody likes Academy Darius, not even me. It's good for its price but it doesn't fit and just looks out of place. Lord Darius is picked alot because of the splash art, but the ingame model is just "eh" and doesn't do much. Bioforge Darius is liked because of the cool green colors aswell as the tech look. Dreadnova would probably be the second most purchased, if you could actually purchase it. It's actually a pretty good skin because of the aesthetics. God-King is loved because of the voice over, as well as all the hella cool sounds and stuff. I can agree. Dunkmaster is probably most purchased and/or liked because it's a meme skin. But it's a pretty good skin none the less, and the voiceover is nice
But I like Woad King the best. The model change is my favorite of all the skins. The axe pattern looks clean and not an overloaded mess. The wolf head on his shoulder looks pretty intimidating, and the tattoo things look cool. The splash art is better than all of his splash arts. The best part by far are the blue particles though. It's a simple change and it doesn't even make sense, but I love it. The blue contrasts normal Noxus colors like red that make the skin look so clean.