South Korea
I would put Gochujang paste on the list for South Korea because it is the kind of thing that feels useful once you are home, not just another airport purchase. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. The reason it works is that it gives you a quick reminder of the trip without needing to keep a fragile ornament safe forever.
South Korea
When I think of an easy, crowd-pleasing thing to bring back from South Korea, honey butter almonds is a good pick because it does not need much explanation when you hand it over. I would buy a couple of packets: one to open while travelling and one to bring home unopened, because snacks have a habit of disappearing before the flight. I would rate it higher when it is locally made, clearly labelled and easy to use at home, and lower when it is just tourist packaging.
South Korea
Green plum tea is worth adding because it feels like something you actually noticed while travelling through South Korea, rather than a generic souvenir. It is a good one because people can try it slowly at home, and it makes a nicer gift than a mug with a place name printed on it. The ideal version is modestly priced, not too bulky, and good enough that you would buy it again even without the holiday memory.
South Korea
This is exactly the sort of thing I like bringing back from South Korea: small enough to fit in a bag, but specific enough to remind you where you bought it. Small bottles are best. A local scent, soap or oil feels personal, but it is still easy to pack and usually does not cost airport-perfume money. It is also the kind of thing you can talk about when someone asks what you brought back, because there is usually a little story attached to where you found it.
South Korea
Korean distilled drink, often sold plain or in fruit flavours.