I had a couple of flights on Korean Air last year. Not long haul, just Seoul to Mongolia and back. Good experience. Seoul Incheon is a fantastic airport too.
I realise things are a bit dfferent now (much better) but I still can't forget the accident reports I've read from years gone by.
I wouldn't choose them to fly long haul if I had what I consider to be better options up front flying the aircraft. That would mean worse options in the cabin as far as service is concerned, but so be it.
Each to their own.