Let's see KOs.. BAir, Down Smash, various hits off of the edge, occasional F-Smash, sometimes counters, sometimes DAirs, rarely UAirs, and recently I've been getting some with Up Smash.
If going for the kill when both the opponent and I are at high percentage, I'll go to either Speed or Shield depending on character/situation. For this, it's important to keep in mind that Shield and Speed do not lower your knockback much - requiring only 3-7% more damage on the opponent. Contrarily, if I'm at low damage myself against an opponent at high damage I'll go to Jump or Smash - again, depending on situation.
edit: I'm using this thread in my school essay.