Вкратце: были запрошены реки на корейские сериалы с главными мужиками - НЕ-козлами.
I can't wrap my mind around suggestions like Prosecutor Princess, Goong AND Secret Garden. These guys NEVER were nice. An occasional showing of kindness to your beloved one is someting to be expected unless you're a certified psycho. Next thing we'll hear will be Baek Seung Jo's and Gu Jun Pyo's pleasantness.
I raked my brain (and mdl-list) for something that would fit requirements, most were already mentioned, but nevertheless.
101st Marriage Proposal - the man ia awfully nice, though definitly no bishounen type, not very attractive and pretty awkward, but very cute.s
9 Ends 2 Outs - the guys always supports his girlfriend (stress on the friend part), though not without a little bit of teasing.
Take Care of the Young Lady - the man is basically a herione's servant and though sometimes uses 'tough love' approach, usually caters to her every whim. Besides he's very likable person and loved by everyone, women and men alike.
Bad Couple - the male lead is pretty naive and well-mannered. And suffer for it eventually.
All about Eve - both main men are too good for their own good.
Sweet 18 - the man is not awfully nice at the start, but definetely not a jerk. Plus he's very polite.
Oh! Phil Seung and Bong Sun Yeong - the male protagonist (sic!) is a nice guy, though a little bit on a lousy side.
Cinderella Sister - the guy is so good and adorable it's annoying. The girl, on contraty, can be a cut-throat bitch.
What's up Fox? - the same actor and again awfully adorable (I want to watch him evil!).
Alone in Love - not especially romantic story, but a love story, ex-spouses restore their feelings. The husband is very warm and dependable person.
I watched only one episode of My Girl, but the guy's behaviour really catches the eye. He's a CEO, but not snobby and doesn't belittle anyone, genuinely cares for his grandfather. The girl tried to blackmail him, and he didn't insult her or kicked her out. He hired her, paid her and thanked her. O.O She, in return, sneaked in his house and sold off his tangerines (I love crafty bitches!).
Offtop: personally I like the high lever of agressiveness in Kdramas, especially because the heriones, unlike japanese, are usually pretty kickassing too. But I hate the way they beat up children. No wonder, there is a such high rate of crimes against children in S.Korea.