I obtained achievement for playing as Miku 50 times.
Although I like playing as her, in order to get more achievements I should pick another character.
Thinking back, my second character in Project Diva 1st was Yowane Haku (for some reason I tend to like albino characters). In 2nd it was Kagamine Rin. This time I decided to pick Sakine Meiko. It was a tough choice between her and Akita Neru.