I don't use the Miller for two reasons.
1) Why get the metal closer to the cords than you need to? Using a Miller blade increases the likelihood of trauma and edema of the cords. This is especially true in learners who insert the blade too deep to start.
2) MAC intubations look smoother than Miller intubations. After supervising for a year and watching experienced CRNAs readjust the blade multiple times to pick up the epiglottis it became clear that MAC had improved speed and better optics. I rarely have to optimize the positioning with a MAC blade and non-styletted tube curved in a loop.