I can tell you Sadow has shown powers beyond Sidious,
With his handy-dandy ship.
that Simus and his queer little head is much more impressive than Sidious, his force storm,
You mean being able to be a head and be virtually powerless? Oh yes, most impressive.
and his defeat at the hands of luke,
Luke = most powerful Star Wars character shown.
and that Ragnos was the ruler over all of them,
Could have been politics. But I don't dispute that he was the strongest of his day.
and they dare not challenge him even on his deathbed.
I've went through this.
If you can't understand this as a testament to his power, then I don't know what to tell you.
Just as I thought. You can't tell me exactly what powers he possesses or what powers he doesn't.
Not to mention his nifty scepter had the ability to drain the force from any planet, and had the ability to bring Ragnos back to life.
Oooh . . . then the power of the item quantifies power for the user? Okay.
Sidious still owns Ragnos.
Death Star, Sun Crusher, World Devastators, Death Star II, Tarkin, Death Star prototype, Eclipse, Eclipse II - all belong to Sidious and each could annihilate planets.