In, re: four crop rotation, I'm assuming you've read/are talking about Master of Ragnarok? I've read few isekai, but that one seemed overall tolerable. The world is not given to the protagonist on a silver platter, he actually has things go wrong and makes mistakes, and the unwanted harem seems more for laughs than an endorsement of polygamy. It has its problems, but it also has some genuine quality, in my opinion.

I've also read a Western isekai/litrpg/xianxia crossover called The Ten Realms, which has its own issues, but does bring a unique take. The heroes are former US military personnel, and their power stems from their philosophies of freedom and self-improvement more than having guns in an overall low-tech world.