Everybody criticizes Isekai, and for good reason. They're formulaic, feature really obnoxious characters, all look the same, and can often be misogynist power fantasies. On the other hand, they're very popular so they must be doing something right. Do you have any isekai that you think are really good, in terms of being fun to watch, artistically worthwhile, and not leaving you feeling gross afterward?
A couple ideas:
Inuyasha - this one's older, from when Isekai stories were usually Shoujo instead of Shonen. It's way too long, but has fun characters and cool monsters.
Tanya the Evil - "The Nietzschean Isekai". I won't spoil it, go watch the first five or so episodes for a wild anime ride. Unfortunately, Tanya the Evil never really progresses any further than the insane premise, so the second half really drags. Also, the art looks terrible and makes me feel terrible in my soul.
Re:Zero - Subaru's story has a lot of the Isekai tropes people hate, not least of all the character of Subaru himself. But, it's full of wild characters and bizarre situations. What I like about the plot is how it makes you think about the different perspectives of the characters as you uncover the reasons for their surprising actions.
I think one thing to look out for in isekai is and I hope I'm using the term right cultural imperalism. If the mc enters the world and starts teaching the residents there how to think and do that's a yikes from me.
Re-zero felt cool to me because the world and it's politics was alive so Subaru has to catch up and learn. Return by death is both powerful and weak because he can't just save spam he actually has to learn and overcome his short comings to progress.
One you haven't mention was digimon which I liked because it was a group of kids playing off each other. What I remembered about the third season I liked but that was more reverse.
There are some good fanfics that handle the genre well if you're interested. The first is a naturo fic where the author tries to weld canon with filler and make a breathing world, called Dreaming of sunshine. The other is a one piece one called This bites. They both are fans of the story and have to navigate the politics carefully. There is also effort in exploring the superpower system from an outsiders pov.
Yeah, the most unironic one that comes to mind is GATE (which I believe is still used in JSDF recruitment). It came out before GATE, essentially the same but outbreak company starts off with the protagonist being used as Japanese soft power against the inhabitants of the other world, but then he figures out and feels bad about the fact that he's an imperialist tool.
One that I like even though it follows this concept is that time I reincarnated as a slime. I justify it in my mind with the world is more a video game than anything really. I'm like 5 episodes in but I like it.