You're Beautiful is on Netflix??? AHHHH!!!
BOF is my favorite. The acting is amazing. City Hunter has the same actor that plays Gu Jun Pyo (Lee Minho) And I think he's an amazing actor, not just a pretty face)
Secret Garden is VERY popular, though I have not seen it. The guy and girl switch bodies, if that sounds interesting to you, then watch it
Playful Kiss is really good, but I wouldn't say it's one of the best. If you like Kim Hyun Joong (Ji Hoo from BOF) then know, that he is the male lead, but his character is a lot colder. I own this drama, but KHJ is being investigated for domestic abuse and I'm not his biggest fan right now (prepare for the thumbs downs)
You're BeaUtiful is one fo my top favorites, rivaling BOF. I didn't think I would like it, but it's amazing! Park Shin Hye is a very popular actress right now, and she plays the female, disguising herself as her brother. The male lead is played by Jang Keun Suk, and unlike most gender bender dramas, he finds out early on that she is a girl and keeps her secret. He's an amazing actor!!! (side note: I don't think it's on Netflix, but his other drama "Mary Stayed Out All Night" is another must see)
The others I have not seen, I'm sorry. But out of the ones I have seen, I recommend BOF and You're Beautiful. If you need more recommendations, message me anytime.