Bubbles is more emotionally enduring than Bell.
I don't want to be 'that guy,' but all evidence points to the contrary. Bubbles has proven to be very emotionally unstable
. Like breaking into tears at the snap of your fingers or going into a battle rage causing her to become the most powerful thing they have ever seen or 'Hardcore mode.'
She can be dangerous if the switch is flipped, but she has never proven to have any semblance of control over her emotions ever. If any of the sisters has less emotional control than Bubbles, it's probably Buttercup- or at least WAS buttercup, but she underwent serious psychological and physical training from a time-traveling magical samurai. I'm sure she's the 'most' balanced now.
Too many inconsistencies, I cannot agree with this without some kind of proof of character development.