User blog comment:FairyTailFan/Juvia not as strong/@comment-5871436-20130609171145/@comment-7418318-20130610154912

Fairy Glitter shouldn't even be considered in any comparison.

Cana can't use it by herself. The two times she used it, Mavis Varmillion lended it to her and it disappeared when the job was done.

As far as pure magic power and potential goes Cana might be Juvia's rival, but in terms of magic they already know (and can use at any time, without special requirements) I don't see Cana being able to keep up with Juvia, even before 2nd origin was tossed into the mix.