The mods are still in the extremely early stages compared to their Koikatsu counterparts aside from a few that were able to be ported with minimal changes, there is still much to do before they get to where the Koikatsu versions are. Of course, that is never going to happen because there is way too much of a head start for the Koikatsu versions, you can only overcome so much in programming and time is not one of the things you can overcome. Even when the mods get to where the Koikatsu ones are now, unless the Koikatsu mods completely stall in development, the Koikatsu mods will have improved even more.
Let's take KSplug for example, Kplug has a vast amount of functionality and is still being developed for Koikatsu even now with more positions and other functions. KSplug is not going to be able to overcome that, by the time Kplug is out of development, we will likely be several games into the future and KSplug will have to be given less priority, and a resulting slower development, to newer variants of the Kplug mod assuming there even is a new variant, which is dependent on the games Illusion makes after this.
I'm in no way saying that the versions out now are not good, what I am saying is you really can't compare the mods between games of completely different years when there is a time gap like that between Koikatsu and Koikatsu Sunshine, comparing them will always result in 'no, the original is still better' unless modding for the original stopped completely already. It is basically like comparing Honey Select to Honey Select 2, Honey Select wins by a wide margin when it comes to mods because there is a significant time gap in which Honey Select modders had time to mod.
The game itself is largely a copy/paste of the original with minor art and mechanical changes as far as what the player sees, so it basically IS Koikatsu, just with slight changes. If you were to go into the code, you would see a different story, but that is in the code, where players usually don't see.
