Kick serve aimed at the middle of the box (i.e. body serve).
There's good margin for error (middle of the box), and my opponent will have to side-step to either their left or right before they can swing at it. If you kick the ball up above their shoulder, you'll typically get a weak return.
USTA computer-rated 4.5
4 matched Wilson Steam 99's / 4 matched Tecnifibre TFight 325 TPs