Recommendations

An immortal waits for centuries for a maiden to break a curse that prevents him from moving on. Even the promo art is reflective of each other.

Both male main characters have an illness that makes it difficult to be a doctor but both pursue to be doctors and do their best despite their weaknesses.
Both dramas have romance between doctors and residents. It's not the main focus of either story.
Medical mysteries do not overwhelm the story with things to do so that there is no more room for character development. Characters build a strong relationship with each other and with themselves.

Autumn Tale isn't a period drama, but there are similarities:

Both are beautiful, heartbreaking love stories. I cried the most watching these two love triangles (or other rectangular). Both are tragedies.

Both shows are socially tragic and both depict the struggles that occur in the upper echelons of Korean society. Furthermore,both shows feature leads who are loyal dogs to the upper class though not high class themselves but have the know how to bring down their glass houses

In both these sageuk, the crown princess/queen selection is a focal point of the intrigue.
The crown prince/king prince influences on the selection process because he's already smitten.

They both have the cinderella type of story when it comes to their female leads.
story both includes a grim reaper.
you'll cry so much on the ending.
age gaps on male & female leads

It is the sequel to the first season so it's the same setup and with a few of the same players, so if you liked the first season you might like the second.

Both characters are sent to a place that deals with animals that they aren't familiar with. Both leads end up liking farming and make good friendship along the way.

They are both about catching bad guys in bad guys technique.
The main leads are in both shows are parents who lose their kids due to the unjust people of this world.
There are hackers and fighting experts.

Great team with cool male and strong female character. light hearted funny and a great ending. No sappy dramas. No harem. No female have to choose which male is for her (thus no endless wishes from the audience that the female should be pair with the other male)

The concept is somewhat similar where both leads time travel to each others' world with an unknown reason. Hence, they try to figure out what is going on and how to travel back to their own worlds. Along the way, they end up falling in love with each other.

Both female leads time travel to the past. Difference male lead from Dreaming back to the Qing Dynasty gets to meet the female lead in her time, and the male lead in the Cinderella doesn't meet her until she gets to the past.

So to be married couple. Complicated relationship. Secret love affair. Male chases female first . Strong female. Nice male lead

both leads are "twins" in TCC he isn't related and is more of a doppelganger someone they find that look a lot like the king, where as in QLAW they were actual siblings.

If you like the few BL scenes in Slam Dance and want to see Drake in a full on BL series, then give ‘Cause You’re My Boy a chance. Some argue that the story is bad and they are not wrong, but it’s still a fun watch!