My all time favorite in this category is
Cruel City - gangster action drama with a lot of fighting scenes, strategics, treason but also unexpected loyalty and honest feelings
My Beautyful Bride - the fiance of a bank employee get kidnapped. He will learn more about her dark past but nevertheless do everything and fight everybody to get her back.
Others I could recommand are not in a modern setting but at least during the 1930th. Maybe you give it a try:
Inspiring Generation -the lifetime story of a village-boy who becomes one of the most famous gangsters of Shanghai.He is strong, calm and kind hearted but show no mercy if he protects what he loves. He becomes very intelligent and cunning while time being. If you like martial art as well, this is a great drama.
All three of them are more dark than for example City Hunter, but maybe you like them.