I have compiled a list of the idols with the most #1 songs on Gaon (Circle) Digital Chart since 2010. Group songs, solo songs, appearances as featured artist and collaborations are included.

1. IU - 30 songs

As lead artist (23 songs):

2010: Nagging (ft Lim Seul-ong), Good Day 

2011: The Story Only I Didn't Know, You & I, Someday (soundtrack)

2012: Every End of the Day 

2013: The Red Shoes, Friday (ft Jang Yi-jeong) 

2015: Twenty-Three, Heart (soundtrack)

2017: Through the Night, Can't Love You Anymore (ft Oh Hyuk), Palette (ft G-Dragon), Autumn Morning 

2018: Bbibbi 

2019: Love Poem, Blueming

2020: Eight (ft Suga), Give You My Heart (soundtrack)

2021: Celebrity, Lilac, Strawberry Moon, Winter Sleep 

As featured artist and collaborations (7 songs): 
2010: It's You (Sung Si-kyung)

2014: Not Spring, Love, or Cherry Blossoms (High4)

2015: Leon (Park Myung-soo) 

2017: Love Story (Epik High)

2018: SoulMate (Zico) 

2021: Nakka (AKMU)

2022: Ganadara (Jay Park) 

2. Taeyeon (SNSD) - 18 songs

As lead artist (7 songs):

2015: I (ft Verbal Jint)

2016: Rain

2017: Fine

2019: Four Seasons, All About You (soundtrack)

2020: Dear Me

2022: INVU

As featured artist and collaborations (2 songs):

2010: Like A Star (The One)

2017: Lonely (Jonghyun)

With SNSD (9 songs):

2010: Oh, Run Devil Run, Hoot 
2011: The Boys

2012: Twinkle (SNSD-TTS), Dancing Queen

2013: I Got a Boy

2014: Mr.Mr

2015: Party 

3. G-Dragon (BIGBANG) - 16 songs

As lead artist (3 songs):

2012: That XX

2013: Who You?

2017: Untitled, 2014

As featured artist and collaborations (2 songs):

2011: Having an Affair (Park Myung-soo & Park Bom)

2017: Palette (IU)

With BIGBANG (11 songs):

2011: Tonight, Love Song

2012: Blue, Monster
2015: Loser, Bang Bang Bang, If You, Let's not fall in Love
2016: Fxx it 

2018: Flower Road 

2022: Still Life 

4. Taeyang (BIGBANG) - 12 songs

As lead artist (1 song):

2014: Eyes, Nose, Lips

+

The 11 songs with BIGBANG as seen above 

5. Hyolyn, Soyou (SISTAR) & Park Bom (2NE1) & TOP, Daesung, Seungri (BIGBANG) - 11 songs

Hyolyn & Soyou 

with SISTAR (9 songs):

2011: So Cool

2012: Alone, Loving U

2013: Give It to Me

2014: Touch My Body, I Swear

2015: Shake It

2016: I Like That

2017: Lonely

As lead artist (2 songs):

2013: One Way Love (Hyolyn)

2014: Goodbye (Hyolyn - soundtrack)
As featured artist and collaborations (2 songs):

2013: Stupid in Love (Soyou with Mad Clown)

2014: Some (Soyou with Junggigo ft Geeks' Lil Boi)

Park Bom

with 2NE1 (9 songs):

2010: Try to Follow Me, Go Away

2011: Lonely, I am the Best, Ugly

2012: I Love You

2013: Falling In Love, Missing You

2014: Come Back Home

As lead artist (1 song): 
2011: Don't Cry
As featured artist and collaborations (1 song):
2011: Having an Affair (GD & Park Myung-soo)

TOP, Daesung, Seungri
The 11 songs with BIGBANG as seen above

6. CL (2NE1) & Suga (BTS) - 10 songs

CL
As featured artist and collaborations (1 song):

2015: Daddy (PSY)
+ 
The 9 songs with 2NE1 as seen above

Suga
As featured artist and collaborations (2 songs):

2020: Eight (IU)

2022: That That (PSY)
With BTS (8 songs):

2016: Blood Sweat & Tears

2017: Spring Day

2018: Fake Love, Idol

2019: Boy With Luv

2020: On, Dynamite

2021: Butter

7. TWICE & Tiffany, Seohyun (SNSD) & Dara, Minzy (2NE1) & Bora, Dasom (SISTAR) - 9 songs

TWICE

2016: Cheer up, TT

2017: Knock Knock, Signal, Likey, Heart Shaker

2018: What is Love?, Dance the Night Away, Yes or Yes

Tiffany, Seohyun
The 9 songs with SNSD & SNSD-TTS as seen above

Dara, Minzy
The 9 songs with 2NE1 as seen above

Bora, Dasom
The 9 songs with SISTAR as seen above


8. AKMU Suhyun & rest of SNSD & rest of BTS - 8 songs

Suhyun
As featured artist and collaborations (1 song):

2014: I'm Different (Lee Hi ft Bobby)
With AKMU (7 songs):

2012: You Are Attractive

2013: Crescendo

2014: 200%, Time and Fallen Leaves

2016: Re-Bye
2019: How Can I Love the Heartbreak You're the One I Love

2021: Nakka (ft IU)

SNSD 
The 8 SNSD songs listed above (besides Twinkle)

BTS
The 8 BTS songs listed above

9. Zico (Block B) & AKMU Chanhyuk & SNSD Jessica - 7 songs

Zico

As lead artist (6 songs):

2015: Boys and Girls (ft Bablyon), Eureka (ft Zion.T)

2016: I Am You, You Are Me

2018: SoulMate (ft IU)

2020: Any Song 

2022: New Thing (ft Homies)

With Block B (1 song):

2018: Yesterday

Chanhyuk
The 7 AKMU songs listed above

Jessica

The SNSD songs listed above (besides Twinkle and Mr.Mr)

10. Jang Hyunseung (Beast/Trouble Maker) & Jonghyun (SHINee) - 6 songs

Jang Hyunseung

With Beast (4 songs):

2012: I Knew It

2013: Will You Be Alright?

2014: No More, Good Luck

With Trouble Maker (2 songs):

2011: Trouble Maker

2013: Now (There Is No Tomorrow)

Jonghyun

As lead artist (2 songs):
2015: Déjà-Boo (ft Zion.T)

2017: Lonely (ft Taeyeon)
With SHINee (4 songs):

2012: Sherlock

2013: Dream Girl, Everybody

2015: View