Journey to the West

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.

Must watch 1 then 2. Monkey is a different actor but still a good show, the rest of the characters are the same. Classic journey to fight monsters & saving their master from them.