Buono! is my second favorite J-pop group. They are awesome, and have a wide variety of songs. Most are preppy and cute, others are relaxed, others are great for dancing, and so on! There are three member of Buono: Natsuyaki Miyabi, Tsugunaga Momoko, and Suzuki Airi.
Here are some of their songs:

My Boy

Kokoro no Tamago

Take it Easy

Kiss Kiss Kiss

As you can see in the videos above, they also do a lot of dance shots and PVs. If you liked these, I hope you'll continue to listen to their songs!