my personal ranking 1. Ai - she revolutionized the singing style in MM. 2. Sakura - she's like the reincarnation of Ai, but also with her own style of singing. 3. Maki - a deserved ace status. Daite yo please go on live performance will always remind me what a great singer (& dancer)she was. 4. Natsumi - such a sweet voice. I won't categorize her voice as a strong one, but she has such a soothing voice that will calm my soul. 5. Miki F - similar to Natsumi but a bit more power in her voice. 6. Hitomi - she is so underrated as a singer. She has such a versatile vocal. She was perfect in Mr Moonlight and nobody does it better than her (including Ai). Her part in How you like this Japan sold me. 7. Kei - I just love love her voice. I just do. No reason needed. 8. Reina T - she has such a good vocal control, she can easily be a vocal trainer. And her stamina is insane. Imagine singing Tsugi Tsugi Zoku Zoku alone without losing her breath. 9. Rio K - I can see her taking main vocalist role after Oda grad. she is improving with each single. 10. Eri - I'm into her soft voice. Her voice is made for ballad/spring-like song. Whenever i think of her voice i'll imaging spring right away. Honorary mentions Risa - her vocal is made for rapping. So underrated Mari - stable voice, never a letdown Kaori - the most unique voice in MM. an acquired taste i guess. Aibon - the 'idol' voice Nozomi - so underrated. surprisingly a good vocalist. Linlin - she shines when the song fits her voice, just a bit unstable sometimes. Haruka I - she is improving like a beast. potential main vocalists with Rio K Voice that i secretly adore Sayumi - autotune queen. the worst singer to a bearable singer to a somewhat good singer. Ako - a deep voice. Her voice is mesmerizing. more deep voice in MM please. Masaki - i love how she played with her voice, like every live performance, she changes how she sings her lines. Voice that i secretly hate - Koharu XP - i love Koharu but i can barely listen to her Kirarin voice lololol
Finally someone giving aibon her credits! I think she is often overlooked in vocal rankings, but she is definitely up there. My fave is Oda, simply because in my opinion she has the most versatile voice and her performance in general is good, great dancer and stage presence.