Yeah, we have no clue what his upper limits are, but the characters who have “busted planets” such as Nihilus and Vitiate don”t have lightning or TK feats even close to what Palpatine is able to do casually, (hell, not even Abeloth does). So we don”t know if Palpatine is a planet buster in RoS, but he”s definitely more powerful than Legends planet busters.
Now imagine what Valkorion would do to a fleet when in proper strength. There should be no doubts about Valkorion - he is SUPER in every category of Force Power. His choices are another matter.
I like the aspect of Valkorion being focused in his exploits, to minimize attention rather than leveling environments and boasting about his exploits on a frequent basis. Hall Hood have a similar viewpoint.
When Valkorion decided to devastate a WORLD to send a message across, he pulled it off with just a blast of power. He reduced every Force-user on the surface to dust in the process. And not any ordinary planet but a very big one with a massive populated base and multiple moons orbiting it.
Valkorion is without any doubt stronger than any individual Jedi or Sith.
Palpatine is a showoff.