Sukuna, Hollow Ichigo/Shirosaki, Kurma/Kyuubi, oh lord...
And a lot of self declared major fans were saying Luffy wasn't getting possessed, he hadn't changed and his DF isn't influencing him lmfao.
DFs are meant to be an eternal curse for as long as you live I mean, so it's fitting such a legendary, literally godly even fruit would be the most cursed potentially or close to it.
I think the Yami is the most cursed though as that would be more fitting and it's called the most evil fruit too.
Nika being more of an anti hero, more morally grey or "edgier" and thus more unpredictable, crazier, dangerous etc would be interesting.
Could even necessitate Shanks, Dragon or Garp for example to conflict with Luffy and feel they have to stop him or "Nika" technically.
I'd love for Nika to be a more nuanced and not truly heroic/pure/goody two shoes character.
One Piece LOVES subverting expectations and making certain characters ironic subversion of their real life counterparts and given Joyboy is based on King Joyoboyo/JAYAbaya IRL, an Indonesian king, this could get VERY interesting potentially too.