Forgive me, and you will certainly want to double check the equipment operating on your specific dates, but I believe the Korean and Malaysia 777 seats in business class are essentially identical. I believe they are/were manufactured by B/E Aerospace. Also used in the previous generation for JAL (Shell Flat).

In this case I'd stick with MH, it's not worth the $$ premium. And, having experienced both, I think the Golden Lounge in KUL is actually nicer than the KE lounge in ICN. YMMV but it's a tossup and, in this case, $$ wins.