* Ariake @ Hotel Shilla (Jang Chung-Dong, north of the river)
Pretty good quality wagyu and nice balance of sauce.
* Omuraan (Yeok Sam-Dong, south of the river)
This is actually a famous soba shop run by a Japanese chef family, but its donburi and sukiyaki are also quite nice. Cozier and more reasonable price than Ariake. Check if they still serve sukiyaki before you go, because I tried it long time ago.