HPMOR is my all time favorite book, I've read it multiple times and I am still in awe of it. From the same genre I liked stuff from Alexander Wales, mainly The Metropolitan Man [1], The Dark Wizard of Donkerk [2] and, to a lesser extent, Worth the Candle which was just finished.

While not really intended as rational fiction, Threadbare was a nice read too if you enjoy litRPG.

[1] https://www.fanfiction.net/s/10360716/1/The-Metropolitan-Man [2] https://alexanderwales.com/the-dark-wizard-of-donkerk-chapte...