I did a similar list for 2019 last year and not all drama managed to air in 2019. Nevertheless, they did not disappoint me at all.
#1 Welcome 어서와
Starring: Shin Ye Eun, L (Kim Myung Soo), Seo Ji Hoon
Original network: KBS
It is a fantasy-romantic comedy about a cat (by L) who transforms into a human. The drama will start on the 2nd March (yet to be confirmed).
Source (1)
#2 The King: The Eternal Monarch 더킹: 영원의 군주
Starring: Lee Min Ho, Kim Go Eun
Original network: SBS, Netflix
The drama is set to air in the first half of 2020.
Source (1)
#3 I will go to you when the weather is nice 날씨가 좋으면
Starring: Park Min Young, Seo Kang Joon, Lee Jae Wook
Original network: JTBC
Rumor says that they will air in Feb 2020, however, JTBC only revealed that they will be airing the drama in the first half of 2020.
Source (1)
#4 Touch 터치
Starring: Joo Sang Wook, Kim Bo Ra
Original network: Channel A
The drama is about romance between a 10 years trainee and a popular makeup artist. The trainee end up working alongside as an assistant to the makeup artist. Starting 3 Jan 2020, we are able to catch this romance drama.
#5 Itaewon Class 이태원 클라쓰
Starring: Park Seo Joon, Kim Da Mi, Yoo Jae Myung, and Kwon Nara.
Original network: JTBC, Netflix
Based on a webtoon of story of youths who fight against unfair world. A group of people open up new businesses in Itaewon, Seoul.
State to air in Feb 2020.
Source (1)
#6 The Way He Remembers 그남자의 기억법
Starring: Moon Ga Young, UP10TION’s Lee Jin Hyuk
Original network: MBC
The drama is set to air in March 2020.
#7 Psycho But It’s Okay 사이코지만 괜찮아
Starring: Kim Soo Hyun, Park Shin Hye
Original network: tvN
Probably the first full drama role that Kim Soo Hyun is in after discharged from the military.
Source (1)
#8 Half of a Half 반의 반
Starring: Jung Hae In, Chae Soo Bin
Original network: tvN, Netflix
The rom-com state to air in Feb 2020.
Source (1)
#9 Ssanggab Cart Bar 쌍갑포차
Starring: Yook Sung Jae, Hwang Jung Eum, Choi Won Young
Original network: JTBC, Netflix
The rooftop cart bar that only operates at night and customers consist of humans and the dead. The drama should be aired in the later half of 2020.