Finished and unfinished. I’m not including every single one of the newer isekai series, there’s too many of them. Many of them follow the same base formula with differing variations, which gets kind of redundant. I included a lot of older series I've read because Romance Fantasy has always been a thing and the Isekai genre is a whole tradition.
Here's a list of the completed Manhwa:
https://www.mangago.me/home/mangalist/2671816/ 
Pandora Hearts