This won't be a face-slapping focused novel or a story centered in the MC fucking (Yeah, I'm sure I set this novel to not be recommended to minors) any beautiful woman near him, women in this story will have their own vocations, and personalities, rather than serving only to be trophies.
The antagonists (at least most of them) will have brains and won't act based on mere childish emotions such as: "Hey, I'm more powerful than you, so I will try to humiliate you just cause I have nothing better to do, I'm sure I can live the rest of my life like this without ever meeting someone brave enough to kill me, I'm so smart."
The plot won't be the same "The people of this world are useless, so I, the mighty MC, am the only one who can save them."
The MC won't act like a kid just because he was reborn in another world, but he also won't act like a "Gary Stu/Marty Stu" (it's cringe) just to be in the limelight all the time. He will act cautiously but he ISN'T a psycho who thinks and acts as if his life is the only thing that matters, he will have emotions, sometimes uncontrollable ones, as any ordinary human being.
If you are someone who puts harem as a pre-requisite, I can only say I have no hate or preference towards this genre, and I prefer to make you wonder if it will have a harem or not. I, myself, am yet to decide.