Soul to Seoul is a good one! I like it.

Id

I recently discovered this one. I quite enjoy it.

I found these manhwa really enjoyable-

Goong
Cutie Boy
Boarding House of Hunks
Peppermint
Bring it on!
100% Perfect Girl
Can't lose you

Some have already been said, but I'll recommend them again 😮

Ingènuo
not exactly genderbender because she only cross dressed for 1 or 2 chapters but overall its pretty good

[img]http://i293.photobucket.com/albums/mm52/MeeeisMeee/thkatie.jpg[/img]

best art would be "the bride of the water god"

Your mom goes to college.

1. Superior
2. Gintama
3. The bride of the water god
4. Chevalier D'eon

They Too Love
Cynical Orange
Ice Kiss
My Girl
Vanilla Ice
Hot Blooded Woman
Angel Shop
Yaya
Zippy Ziggy
Good Luck
Kill Me Kiss Me
Show Me the Money
The Kidnapping of Minja Jo's Boyfriend
Red Lion
Vitamin
Blooming (Bring it on)
And of course, Goong, and some on my wishlist, Hush, Can't Lose You, Cutie Boy, Death Song, and Will. 😲 Wow! I've read a lot...

For the people who mentioned Ingènuo and Show me the Money: they are both very good manhua, but are Chinese (Taiwanese), not Korean.

Some good lesser read Romance manhwa I would recommend are;
H20
Crazy Love Story (quite deep and psychological)
One
Do-Re-Mi-Fa-Sol-La-Si-Do

You don't like gender bender! ah~ And I was going to recommend Saver, even though she pretends to be a guy, she still looks totally like a girl with her flowing long hair. (sorry, I dont' know how to link this stuff, hehe)
-Bride of the Water God
-Red Lion
-Dear Waltz
-Chiro Star Project(wait scratch that, i think there's gender bender in it)
-My Girl
-Yaya
-Evyione
-100% Perfect Girl
-Boarding house of hunks
-hot blooded woman
-Goong
-Cynical orange
have fun 😉

♪MONSTARR~ will eat all your cookies and steal your bishies~♪ Φ_Φ

I too recommend Unbalance X2