I think that Phoenix is probably the most powerful, with Storm being a close contender. I place her over Rogue because Rogue has to have tactile touch to get say, the Phoenix's powers. But Phoenix could vaporize her before she could get that close, and even Storm could call down something terrible from the heavens. So my list is:

1.) Pheonix

2.) Storm

3.)Rogue

Sorry guys for the lack of information on why I chose these selective people. I was in a rush and I have horrible reception right now.

@mistresssobeautiful:

when you say Phoenix, do you mean Jean Grey, Rachel Grey, or the Phoenix?

@oldnightcrawler: I mean Jean Grey

Darwin

Probably Storm and Rogue.

Legion- He has multiple abilities to choose from and is unlimite d in those choices. Argruably the most diverse powerset in X-men history.

Storm- Many people don't know this but Storm doesn't mearly just control the weather but the energy and forces behind them all on a sub-atomic level. Ranging from kinetic, thermal, electrical and electromagnetic. All of these forms of energy have great potential to be explored.

Magneto/Sienna Blaze- The Electromagnetic Spectrum holds an array of function and is second only to the Strong Nuclear Force. This ability gives them access to nearly limitless potential.

Jean Grey/Rachel/Cable/Nate- Telekinesis alone is a well versed ability given the possibilities of manipulating all forms of matter and energy but the added bonus of telepathy makes this combo one of the most deadliest powersets. Within the realms of the mind they are limited to only their imagination.

Scarlet Witch- Chaos magik or no, being able to manipulate the outcome of circumstance is well versed to me.

Franklin/Mr. M/Mad Jim Jaspers/Jamie Braddock- Reality alteration is no doubt the most versatile powerset. The only limit is their imagination and ofcoarse reality.

Phoenix. Basically any high end psychic with both telepathy and telekinesis at highly realized levels are more versatile than pretty much any single or limited phase energy manipulator.

Excellent list and fully agreed.

I'll also mention Hope and Rogue (RIP) since they have the power to copy and combined all of these abilities.