After reviewing your lists, here's what i recommend:
1. drop everything and watch My Only Love Song....its fast moving, cute as hell rom-com. Short and sweet. 20 30-min eps produced by Netflix. You'll knock it out asap. Its has both modern times and historical times because theres some time travel involved. its especially great to watch while you're strategizing on your other dramas that are a much longer commitment.
2. then watch Fated to Love You (Korean version) - While you may know the story from the taiwan version, the acting by Jang Nara and Jang Hyuk is so amazing that I am an emotional roller coaster each time I watch it based on their expressions alone. I watched part of the Taiwan version and they feel completely different
3. I would take the time to watch reply 1988. It is a super well-done drama that sticks to your bones. Forever.
4. And here's a movie i recommend if you want another quick rom-com. Ji Sung is dripping in sexiness in this. Watch this as a palate cleanser in between any of the above! My P.S. Partner.
Enjoy!