You cannot have this conversation without Rudeus Greyrat. Why it’s top tier: This is the Lord of the Rings of the genre. It actually commits to the "Monogatari" (Story) part. Rudeus is a flawed degenerate, but the harem (Roxy, Sylphie, Eris) isn't just fan service; it is the emotional engine of his redemption arc. The animation is movie-quality, and when he finally marries them, it feels earned. Verdict: The standard by which all others are judged.
This is the ultimate "guilty pleasure" isekai. Protagonist Touya accidentally gets killed by God, so God lets him keep his smartphone in a fantasy world. The series is low-stakes, high-comfort, and the harem is enormous. isekai harem monogatari top
Diablo (aka Takuma Sakamoto) is a shut-in MMO god who gets summoned into the game world by two girls: a Pantherian and an Elf. To avoid looking weak, he roleplays as the "Demon Lord" character. What follows is a masterclass in ecchi comedy. You cannot have this conversation without Rudeus Greyrat