Since I'm a girl, I'll go for the game's antagonists. They're affluent and influential enough for me to live comfortably without necessitating extra contribution from me. All they want is some sexy, and assuming isekai me is attractive enough for them to act on the notion of stealing me away, I'm pretty sure I can work something out.
Korean idols are a lot more under their agency's thumbs than we think they are (unless you really know your salt in those specific circles), and that means I as their partner would have to deal with that drama plus their emotional episodes (it's sex, and neither party is an inanimate object); and the extraterrestrial requires effort and work to live with and even understand. By method of elimination, I'm left with the three antagonists.
If it were a guy...maybe the extraterrestial? That it could come in and just nab my girl would mean there's very little I can do about this, which, I don't know, lessens the despair?
It's a very interesting perspective. When I wrote these questions, I assumed that everyone on this forum is male, my mistake. I should have also provided more details for each option.
Consider this: What would frustrate you more, or what would you prefer?
Which one generates more emotions in you?
(Keep in mind that you are the protagonist of the game and can change the gender of your harem to fit your preferences)
1- A group of three men with Korean idol-like features stealing your harem (they are just three very handsome men, they don't possess powers, but their beauty gives them a certain persuasion over others).
2- The three antagonists of this game stealing your harem.
or
3- An extraterrestrial stole my harem (One night, a small UFO crashes in your backyard, and your girls decide to take care of/raise it as a pet). Note: the extraterrestrial is conscious of everything and can change its size and shape at will.
There is no correct answer; only perspectives.