Sky Hub Lounge is located on the 4th floor of the Incheon Airport. It's a smaller boutique lounge, and if it gets busy, there's a wait time.
To get in, you either need a priority card or one of the credit card companies affiliated with them. Entrance fee is USD 36 which may not be worth it unless you have a long layover.
The food there is surprisingly pretty good! Don't expect it to be a 5 star restaurant, but compared to the major airlines, the selection here is definitely better.
I personally really enjoyed the dumplings and beef kimchi soup!
Really enjoyed the different mixed salads as well.
The only downside is the lounge area is pretty cramped. And because Seoul airport is one of the busiest airports in the world, this lounge doesn't seem to have the capacity to cater to the traffic flow.
If food is more important, I would go to sky hub lounge. But if you prefer comfort, more space and showering areas, then I would try out Asiana Airlines Lounge instead.