XSUPREMEXSKILLZ
The Immortal Emperor
The rest wasn't fanfic, once upon a time. And EU! Sheev would be most likely to attack with lightning/TK/Force Storm, depending on incarnation. In the EU, his lightning was powerful enough to completely turn an enormous Sithspawn to ash, turn a dark side prophetess to bone, and was powerful/precise enough to kill dozens of stormtroopers, while only hitting them and not the imperial guards within the crowd of said stormtroopers.
Though ultimately, I don't really have a reason to debate, considering that I can see where you're coming from and how you're forming your conceptions.