From my own UTAU, I want to suggest Senchou VCV Stage. They’re good at rock and pop songs:
My personal favorite UTAU is
Mujika. She’s incredible because she’s completely synthesized voice aka. not voiced by human. If you like an easy CV/VCV voicebank with “Defoko-like” charm, I highly recommend her!
EDIT: I want to add one more my another fav: Kayaka Konagi. She has great English VB and multiple Japanese VCV VBs. She’s very natural and versatile, I recommend her!