Recommendations

Both are based on the tales of Journey to the West. The Journey to the west is closer to the original story and funnier. I also find the Sun Wo Kong here is more active like a monkey, funnier, smarter and real troublemaker than Hwayugi. If you really really like the tale Journey to the West and Sun Wo Kong, I really recommend you to watch this. Even though this drama is old, this is truly a masterpiece.

However, if you want more mellow and romance then choose Hwayugi.

I think both are good in different perspective.

The Great Seducer is a modern-day adaptation of this movie which is considered a classic for Korean films.

Both male leads are playboys who like to seduce and play around without any emotions attached; and they also have complicated relationships with their fathers. They also have a female "best friend" or step-sister with whom they make plans together.

The main couple living together, their interactions and personal traits, the silly faces that the male leads can make are the same, they are especially lovey-dovey

There is romance between 2 childhood friends, though they do not get together. The main couple's relationship and personal traits are quite similar, they give the same feels, they are especially lovey-dovey

In W the male lead is from an other World, and in Hit The Top he is coming from the past.
Though that was just the only similarity. They give absolutely different feels.

Both main leads go through character growth that make you fall in love with them. All the main characters bring out empathy from the watchers. They both deal with court/law. Lee Jong Suk and Park Shi Hoo's characters lean more to the anti-hero side then the hero side, straddling the line between dark and light. Both will get you hooked once your past the first episode.

This drama has a very similar feel to Circle. They both feature scifi, suspense, mystery, with a bit of romance.

The female lead in Threesome has the similar multiple personality disorder as the male lead does in Kill me Heal me

Similar multiple personality theme related to something which happened in the past, the female lead suffers from this issue in "Threesome"

Both female leads can see ghosts and male leads are supernatural beings who cross path with the female leads.
Korean Odyssey is similar to goblin but with everything lesser.

This is very, very similar in the way that Borg Mom was created as a way to comfort the son and in some ways the husband, who created her. Again electronics here. Not television . This is more family oriented and no real romance---although you get feels people. There are feels. Or I had them.

Despite the fact this drama has yet to end this drama is going in the same vein. Young man has a girl who's "out of this world" really. This one is not robotic, but she is electronic. It's like the guy starts having feelings for a woman he can't really have because she's not real.

Incestuous relationships between sisters and brothers. Mainly brothers being highly obsessed with the sister while the sister is in love with someone else. Sister then later gives in to their brothers affection. (exception here-blood relation)

They have similar humor, they both have interesting story going on,in the lover is more than one ,but still hilarious .If you enjoyed on of them you will enjoy the other one too