Blood might be 更多 Powerful (Thanks to the Overrated Dragon Flame) but Stella is much better at using her power and she is much 更多 experienced as well. It may be a close call but Stella shall win in the end.
I am not sure. Bloom has a better power while Stella uses her power better I am not sure .I think I will go with Stella because bloom only uses her full power when she is angry , Stella stayed A 年 before the winx . So yea my pick is Stella