hmm interesting ...
by lightsaber .. it must be Mace Vindu
by force power
Light: Yoda, Revan, and Ulic el droma and probably many jedies i haven't read all books .
Dark: Exar Kun, Dark Nilas, Emperor Palpatine and Kreia
But i'm sure even those names you have mentioned.. it has existed jedies and sith wich was more powerful then those mentioned. by ancent times
but by power through wisdom and understanding...
so far as i see.. is Kreia, Yoda and Obi wans mentor .. (can't remember name tho*blush*)
Those who understand the heart of the force and knows by wisdom whats good or not.
are what i consider most powerful not by how many fancy force tricks or saber forms.. you can.. but how well you understand the meaning to be a Jedi or a Sith and the force.
as Kreia said "the jedi of today are but children playing with toys compared to the masters of old."
just as we in real world tries to understand what is to be a human in a chaostic world and the unlocked knowlegde that exist in our very mind.
yes it sounds very ... zen .. but everyone won't get hurt to thinking deep now and then