Who do you think is the most Powerful in the X-Men comics/movies?

Many will say Jean or Pheonix, Dark phenoix or Apocolypse. I beleive the most powerful is Onslaught. If you do not know who this is then here is a link: http://en.wikipedia.org/wiki/Onslaught_(comics) . Jean is stated in the movies as the only stage 5 mutant but the movie did not, and cannot incorporate all the comics unless they made hundereds of movies. If you like, state who you think can beat Onslaught. Im refering to individuals, seeing as hes put to be one entity, his downfall was due to mive attacks by the Advengers, the Hulk, Fantastic 4 and the X-men team. As stated in the link above.