@criver Honestly, I've never tried to compile a top manga/light novel list before today, but this is what I came up with. Some of the rankings are probably a bit questionable because I haven't seen them in a while and there are a lot of novels that I never logged into my novelupdates reading list and have since forgotten about. Either way, I ended up having 12.5 isekai stories in my top 20. Granted, a lot of them are filling up the 10-20 slots, but I was not lying originally.
1. Koe no Katachi (manga)
2. Three Days of Happiness (LN/manga)
3. [isekai] Moon-led Journey (LN/manga)
4. [isekai] Mushoku Tensei (LN/manga)
5. [sorta isekai] The Magnificent Battle Records of A Former Noble Lady (LN)
6. Shishunki Bitter Change (manga)
7. [isekai] Average Abilities (LN/manga)
8. [isekai] Log Horizon (LN)
9. Hoshino, Close Your Eyes (manga)
10. [isekai] Tensei Shitara Slime Datta Ken (LN/manga)
11. [isekai] Common Sense of a Duke's Daughter (LN/manga)
12. Tomo-chan wa Onna no Ko (manga)
13. [isekai] Isekai Omotenashi Gohan (manga)
14. [isekai] Fiancée's Observation Log (manga)
15. Yuuutsu-kun to Succubus-san (manga)
16. [isekai] World Strongest Rearguard (LN/manga)
17. [isekai] Shinju no Nectar (manga)
18. [isekai] Kumo Desu ga Nani Ka? (LN/manga)
19. [isekai] Tate no Yuusha (LN/manga)
20. Kaguya-sama Wants to be Confessed To (manga)
Keep in mind that being on this list doesn't mean that it's flawless it just means I like what it does. For instance, "Tate no Yuusha" gets pretty shit later on, but the first 50 chapters are still good enough to be worth its spot. "World's Strongest Rearguard" is pretty wish-fulfillment-ish but its depiction of a video game world is amazing.