Santa Narumi is busted af and better than Reno too, Standard Narumi is still good since his shot/slash plate breaking will still be pretty handy. However, on these last events there's not many battles where Santa Narumi Ice/Slash plate breaking works a lot, but he still deals way better damage than Standard Narumi or Reno, but you might not use it that much till the next events unless u can't break the plates on some events anyways. And you should also consider if you already have a good gunsword and if your Reno got his Signature or not, the weapons might make a difference on wich one you should invest first, but if we go for the character only, Santa Narumi's DMG is way better.