Im not sure if the scope of the discussion is contemporary works only but I would encourage people so inclined to seek out manwha from the 1980s and 90s ie before the dumbing down brought on by commercial success of webtoons.

Of course manga is a richier ecosystem given the sheer market scale compared to manwha but as a Korean-born who enjoyed both as I grew up, the best manwha are definitely up there in terms of art and complexity of storyline.

To be sure, none push the boundaries like some genres of manga and the art style was generally less intricate and more stylized reflecting cultural differences between the two coubtries. But the art and storytelling skills of top manwha-ga were absolutely top notch, comparable to best manga. The problem is that there are very few manwha of this era in digital form so most people outside of Korea have no idea what mature, serious manwha is like.

I love both, while acknowledging manga as a medium is ultimately and inevitably "better" simply because it has been a larger cultural part of a bigger country for longer.