They aren't even remotely similar types of festival though, can't compare them.
Indie rock with a little electro house and dubstep thrown in isn't the same as exclusively electronic music ranging from house to trance to d&b to dubstep to techno. It would be like comparing a jazz fest to a country music festival. Totally subjective.
I plan on going to both next year by the way, and no idea which one I'm more excited for!