I play Darius - with breaks - since 2012/13. I have nearly all Darius skins and i totally understand you cross off and kinda dislike skins like dunkmaster and academy (even dubkmaster is well done).
For me insta buy was Woad and Godking. I normally played only woad till godking arrived. It’s sad Woad-skinline doesn’t get more attention but I love every detail about that skin.
Godking in the other hand feels amazingly smooth gameplay wise.
About the other skins:
Bioforge is solid and good but I am not a fan of it.
Dreadnaut is a lost opportunity. Could be a really great skin but I don’t like his visual execution.
Academy... meh (even it’s the imo best academy skin I hate this skinline for me the worst)
Lord was his first skin andi like his classic but classy appearance. Met a Darius main who only played with this skin. I like it but the gold colours are a bit distracting. - But the cape is awesome.