Psylocke
Psylocke is my favorite mutant of all time, I just want to get that out that. I love her, she has the coolest powers albeit with a confusing background (due to her origins in the Marvel UK Prints) but with her being in this new series maybe somethings will finally be straightened out. Elizabeth "Betsy" Braddock is the sister (or was at least, but I still believe this part of her storyline) of Captain Britain, and was at first made as a telepathy that would back him up at times; she was never confirmed as a mutant but there aren't a lot of other explanations for her powers short of being a mutant. While her original powers was purely telepathy, and all the things you think of with those powers, but when she was brought over the Marvel in America she was captured by The Hand and brainwashed. The other thing that went along with this brainwashing was a physical transformation that made look more Japanese rather than looking English, another thing the Hand did was actually clone (for lack of time and how much explanation is needed) her body which weakened her psychic powers. What was very interesting is that she was able to turn "psycho-blast" ability into a psychic dagger which she could drive into the head of her opponents to disrupt their mind (yeah awesome); see after all that brainwashing Psylocke became an expert in pretty every martial art you can think of (from Ninjutsu to Akido and everything in between) and with that she became better at fighting hand-to-hand and up close and personal. While still showing the ability to fire her psychic blast from far away she still likes up-close better. After some stuff went down and some very confusing power switches Psylocke lost her power to use telepathy and gained the power of telekinesis, after getting better at this Psylocke can now conjure up a telekinetic katana. Her most impressive powers though is the fact she can use her telekinesis to manipulate her body to super human speed, strength, and overall fight levels, AND she is immune to almost all psionic attacks and manipulations. She is reportedly the strongest telekinetic in the Marvel Universe right now for her prowess with her powers even though it might seem she uses them in an indirect way. Did I mention she is my favorite mutant.