Shal We Kiss First? - Ahn Soonjin and Son Muhan
I'm always promoting this drama :^)
The main leads in dramas like Secret Forest and Let's Eat 3 have good chemistry but not a "couple."
Other older dramas: Master's Sun, A Gentleman's Dignity, What Happens to my Family? (I like the sister's story), Playful Kiss, My princess, Age of Youth, Jugglers (but this gets boring 2nd half).
Airing Drama: Feel Good to Die.
I bolded my 5 favorites :).