Crash Landing On You: come for the cute, sweet and hilarious; stay for the swoon. I guarantee you will fall in love with actor Hyun Bin, but you will also love every other character: they are all adorable ducklings. This is as feel good as it gets.
Because This Is My first Life: superb acting and writing in this funny, insightful look at modern relationships. Has one of the top 10 K-drama kisses. (You will notice that kisses are few and far between in K drama and you learn to appreciate the ones you get.)
Stranger: (Also known as Forest of Secrets.) Fantastic acting and writing. This is a suspenseful character-based drama about a prosecutor and a cop investigating corruption. Love the relationship between the leads.
Signal: if murder mystery/police procedural with a dash of fantasy is your cup of tea this is a must-see. (Actually, it’s a must-see no matter what your favourite tea is.) Interesting twisty premise and lots of suspense. Tunnel and Voice are also supposed to be very good in this genre, but I haven't seen them.
Inheritors: (Also known as Heirs.) This is a high school Cinderella drama with all the tropes. Saved from utter cheesiness by decent acting and writing, plus actor Lee Min Ho is worth the price of admission.
That should keep you going for a while! There's more, so if the self-isolation continues I'll do a follow-up post. Doing what I can to keep us all sane!