I used to use regular, but the last 3/4 applications I've used mild. Becasue I've come to realize that I would like to have a little more texture and strength in my hair, and regular seems to leave it too straight.
I smooth it out and leave on for a total of 20-25 mins (including application time) apply a reconstructor, and it still comes out pretty straight. But it does have some texture to it still.