Strongest TK is probably Jean Grey's as the Dark phoenix. Able to use it so effectively as to change the molecules of her outfit.
Best Example of TK power tho was Nate grey. He stopped teh snow from falling and the birds from flying as if they were suspended in time.
DC is not big on TK users. Emerald Kinetix might be the most powerful TK user in DC that wasnt' a cosmic.
In Marvel, Jean Grey, as the White Phoenix of the Crown, demonstrates the greatest TK ever, being able to structure an entire universe atom by atom.
Aside from her, Nate Grey comes to mind. He's constantly stated as being the most powerful pure psionic entity there is in the entire Omniverse, the evil Earth-998 Queen Grey stated that the Nate Greys throughout the Omniverse were essentially the ultimate telekinetics within their own universe, and Moira Mactaggart stated, after examining him, that his telekinetic ability may have been beyond the Phoenix's.
He can use his ability in extremely creative ways, for example phasing through material by mentally rearranging the material's molecules, mentally manipulating water vapour and dust particles to refract rays of light and create holograms (both of which also display great pinpoint accuracy), and channeling the Earth's magnetic field through the electric current of his brain to generate EMPS (which demonstrates an extremely high mastery of TK).
... They really need to bring him back from the dead. Easily the best character in Marvel canon.