well i would say it depends... if they are a heavy character, and you are high enough on the stage, the tornado could be the best choice... it will net you a pretty easy (and particularly satisfying) KO if you can keep them inside it until the last hit (the only one with worthwile knockback). To do this you have to keep pressing B. Shuttle loop is always nice, but if youre not off the stage, it will probably not KO them unless they are really high percentage. SL can KO off the top too, if you hit them right but i havent seen it happen too much personally. Also, if neither will kill them, the tornado can still be a decent combo option (again, better on heavier characters) to rack up damage...