I like to eat at this BBQ place whenever I visit the Assi supermarket in North Wales. The highlights for me are always the house-made kimchi and the green salad. Ban chan offerings change frequently and are generally good. I strongly prefer those that are traditional Korean and vegetarian. Sometimes they offer mayonnaise-based potato or mixed-veg salads, or even vegetables covered in a ranch type dressing. These aren't as good, but there are always several ban chan to choose from. The purplish rice is always excellent.
I tend to stick with the bulgogi, BBQ orders, or the bibimbap at Koko, and these are all sure bets. The seafood pancake has been rather greasy and the mandu are acceptable without standing out. The dolsot bowls are truly smokin' hot, which is great in winter time. The minimum requirement for BBQ is two orders, which doesn't come cheap. But you could easily feed four people on the generous portions of those two orders along with the ban chan and rice. Staff are happy to refill ban chan dishes that empty out. A very nice roasted barley tea is provided gratis, and served either chilled or hot, depending on the season.
Overall, I recommend Koko. We are usually the only or among the very few non-Koreans in this place.