Mighty Gunvolt Burst: How would you personally rank all 9 characters based on how fun they are to play?

New fan of the series and absolutely LOVING Mightly Gunvolt Burst ^_^

So far I've only finished playing the game as Ray and found her to be extremely fun to play as considering she's very similar to Zero from the Mega Man franchise :3

Not sure who to play as next but I'd love to hear your thoughts as I'm currently considering either Joule, Call or Copen.