Faster Casting vs Spell Echo

Thanks for all the answers.
I hadn't considered that SE didn't work with some skills and i didn't know it locked you in place. Movement is not one of my major concerns as i'm usually just standing still and casting. I'm more of a casual gamer, not good at moving and using multiple skills.
If i find a SE i'll use it for FireStorm.

P.S. I would use only Minions, if they weren't so dumb and i could set some for offense and some for defense.