Who should i main?

I have 5 monsters in pillar chase 2, but everytime i play i keep switching them, so who should i start maining? (maybe i can try to get them to diamond, but who knows)

https://preview.redd.it/bcgphb2gd1ee1.png?width=1920&format=png&auto=webp&s=6cb7b9c6a40f686e95ddd30b193447c23afb03b1