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Here's a few that I've enjoyed:
Youjo Senki (The Saga of Tanya the Evil): 30 year old Japanese businessman dies and mocks God, who punishes him by reincarnating him as a loli in an alternate WWI Germany. I honestly despise Isekai's but this one was enjoyable.
Cop Craft: A detective and a magical warrior team up to fight crime in a city that separates Earth from another world. Unlike most of the "otherworld" anime you never have to see it, because the anime focuses on the city and the racism between humans and the other species. Pretty good, criminally short.
Shakugan No Shana: Tsundere with magic and a sword teams up with normal human who's technically dead. Fun supernatural action series with 72 episodes, which for me is a great length for an anime.
There are more but I can't think of them at the moment.