I'm willing to compromise with the isekai setup.

You're in a new world. There's magic and sword play and monsters to fight. You get some skills and abilities that give you a decent chance to survive. I'm perfectly fine with that setup.

But what I want once you have been given that setup is an interesting world to explore.

Interesting characters to meet.

Actual challenges and hardships that have to be overcome by the main character.

Real relationships with people that have their own goals in life.

And character growth that happens organically given the constraints of the system.

We have far too many Mary Sue protagonists who never failed anything and never do anything wrong and who have so much power and are just so kind and giving in every single way and everybody loves them and nobody could beat them even if they didn't love them.

We have far too many villains whose entire character Arc is "hurr durr look at me I'm a villain".

And for some reason when those villains get converted into sidekicks they always become comical parodies of their former selves.

And finally, even in a harem situation, the main character should neither be asexual or a man whore. Let him have some feelings about the person he's with and not automatically fall into some unspoken love scenario with the women around him.

If you're going to have romance at all in your isekai anime, let the guy actually have some preferences and pick one person and stick with them.

Like I get it you've got to give people a taste of the familiar but the taste of the familiar is only to lure us in. Once we are in, you need to give us something new and strange and stressful and worrisome and make us doubt the outcome of the next series of events that are going to happen.