If you are basing your list on Force strength, Nebaris, you are indeed quite wrong. You can't claim that Sion's "immortality" is nothing more than the depth of his hatred and willpower; in fact, as I recall, there has been no quotes or evidence made in favor that Sion is anything uber in the Force. The Exile dominated him completely, so in a similar situation, a master manipulator such as Traya, Lumiya, or Sidious would be able to replicate the same feat quite easily.
The presence of Malak and UnuThul on your list also has me curious, as Advent has uberannihilated any argument that proves UnuThul to be anything more than a weakling by Jedi standards, whose sole claim to fame was when the Killiks empowered him through the Force. And, as I recall, when Luke decided to get serious - he put him down. Malak is nothing special, either. His greatest achievement was being empowered by the Star Forge, and yet Revan managed to own him there, even when Malak could siphon the life energy from other Force users to replenish himself. Therein, he's nothing special either.
In "power" and Force strength, my list is the most accurate. Luke, Sidious, Jacen, and Kyp all dominate the list.