Everyone who replied already with an anime from the 80's/90's is correct, in that isekai back then were typically adventure stories about young adults growing up, ironically mostly aimed at teen girls with stories centering young female protagonists with maybe a hot guy love interest (Fushigi Yuugi is kinda the problematic template for that.) The characters usually go into the other world and have a character arc overcoming their weaknesses before returning having saved the world and/or bagging the hot boyfriend. Y'know typical heroes journey type stuff, the original template was more Never-ending Story or Chronicles of Narnia than... Ready Player One I guess.

Buuuuuut post-Sword Art Online that all changed and most of it's all lowest common denominator escapist fantasy. Having said that, it's been done to death so much that there are subgenres within it now (Reincarnating as the Villainess of a Visual Novel, Retiring to the countryside with my middle-aged busty wife, Guillotining the aristocracy with my lesbian polycule) that aren't icky apologia for slavery power fantasies, but sifting through all the trash for half decent (or rather, a different flavour of trashy) doesn't seem worth it to me. Admittedly, lately I've become a media snob who'll never admit in public to watching the Minecraft movie, so take what I say with a grain of salt.

Anyway, more recent recs that stretch the definition of "good"-

• Log Horizon is a probably the best "trapped in a videogame" story just based on the sheer amount of worldbuilding that goes into imagining how a MMO-ized fantasy world would even work, even if all that worldbuilding is in service to making the point that Free Market Capitalism coupled with Keynesian economics is the be-all-end-all ideology. The author got got for tax evasion irl. Stop after S1 tho, the next two seasons try to cram too much of the novels into too short a runtime.

• Grimgar of Fantasy and Ash you could say is the forerunner of shows like Frieren or Dungeon Meshi, where the focus is on the harshness of the fantasy world and the logistics of trying to survive- ironically these things seem to have fallen into the purview of straight fantasy as opposed to isekai, but hey at least this show was trying something different at the time. Has a gorgeous art style. Sadly only got 1 season. Also those other two straight fantasy shows are much better that anything else on this list. Dungeon Meshi especially.

• My Next Life as a Villainess is a thrashy fun comedy about a proletarian inadvertently averting the death of the aristocrat whose body she is inhabiting by dint of acting distinctly un-aristocratic. Most of the comedy comes from watching our heroine unknowingly make everyone fall in love with her, regardless of their gender... by simply not acting on the privilege her position in society grants her. It's really dumb but I honestly enjoyed it a lot.

• I know a bunch of Hexbears enjoyed The Magical Revolution of the Reincarnated Princess and the Genius Young Lady even if it wasn't for me. I liked how aggressively and un-apologetically gay it is tho.

• I hear good things about Ascendance of a Bookworm from people I trust but I haven't seen it myself so I can't say for sure. Including it cos why not.

There's probably other show's that are borderline "good"-ish that I just didn't bother rec here like Re: Zero or Slime Reincarnation, but imo the shows I gave a synopsis of are what I'd actually recommend to people on this board.

edited for clarity