There are several all-girls schools in Singapore that are well-known for their strong choir CCAs. Here are some of them:

1. CHIJ St. Nicholas Girls' School: The school has a long history of excellence in choral music and has won numerous awards in local and international competitions. Their choir CCA includes a Junior Choir, Senior Choir, and Chamber Choir.

2. Cedar Girls' Secondary School: Cedar Girls' has a strong tradition of choral music, with their choir CCA winning awards in various competitions over the years. They offer a range of choirs, including a Junior Choir, Senior Choir, and Chamber Choir.

3. Anglican High School: The school's choir CCA has won many awards over the years, including gold awards at the Singapore Youth Festival Arts Presentation. They offer a Junior Choir, Senior Choir, and Chamber Choir.

4. Raffles Girls' School (Secondary): RGS is known for its strong music program, including its choir CCA. They offer a range of choirs, including a Junior Choir, Senior Choir, and Chamber Choir.

5. Nanyang Girls' High School: The school has a strong choral tradition, with their choir CCA winning numerous awards over the years. They offer a range of choirs, including a Junior Choir, Senior Choir, and Chamber Choir.

It is important to note that while these schools have strong choir CCAs, the availability and quality of the CCA may vary from year to year depending on factors such as the availability of qualified instructors, the dedication of the students, and the resources available