For me, I’m torn between Mushoku Tensei (very good worldbuilding) and Uncle From Another World (has the better direction)
Being a parody, it subverts most tropes of isekai anime. Its humor is exactly my type too.
Honorable mentions:
Most other isekai anime have the same cookie-cutter plot, making them so predictable and boring. Or they have an interesting premise, but waste it with poor writing and dumb characters.
I like Overlord. Its got good worldbuilding but it also doesn’t always take itself too seriously and throws in some comedy every now and then to keep it lively.
I also really liked Knight’s & Magic. There are not enough medieval fantasy / mecha hybrid shows out there, despite anime being the perfect medium for it.
Skeleton in Another World was a fun one once you get past the first episode. The attempted rape scene right in the beginning just shows too much on screen IMO, it would have been better to cut some of it short and show the scenery around more rather than what was actually shown. Very uncomfortable, which I hope is what its supposed to make the viewer feel, but then literally none of the rest of the show is every that intensity. Like it was almost Perfect Blue levels of showing too much for too long.
Re:Zero, Konosuba, Overworld, and That Time I Got Reincarnated as a Slime are some of the best, alongside SAO which started the modern version of the genre.
Mushoku is probably the best by such a large margin i couldn’t think anyone answering different was serious. Log horizon is probably the only isekai that’s done the modern game junk well.
My biggest problem with Mushoku, and why I feel like I literally cannot recommend it, is because of the weird pedo stuff. It would be fine and easy to forget I guess if the show stayed in fantasy mode, but for whatever reason any time there is something slightly sexual the show writers decide to remind the viewer “erm actually the main character is a 40+ year old man.” That just pulls me right out of the show.
The other parts are cool, but that one thing really stops me from enjoying it more.
tensei shittara slime datta ken
Visions of Escaflowne was pretty great. It had basically everything, a fantasy world, giant mecha and a Yoko Kanno soundtrack.
I liked Grimgar a lot.
without it we wouldn’t have many of the isekai animes as we currently do
uhh… spirited away?
mushoku is up there if we are talking about the modern kind of isekai
