The Untamed OST is definitely my favourite. I've been listening to it regularly for months and WuJi is my favourite song. I like Bu Wang, Hen Bie, Qu Jin Chen Qing, Huang Cheng Du and Yi Nan Ping as well, together with all instrumental compositions. The whole OST is to my taste.
The Wolf OST is also good. Sirius is probably my favourite song.
When it comes to KDramas the ones I listened to the most were Stay With Me from Goblin (that song was an obsession!) and I'll be here & Our Tears from Hwarang. There were also a few songs from Are You Human Too? and The Royal Gambler but I forgot their names.