The power you pick will be used in the real world. No other superhuman will exist outside of you. Consider all real world implications of your powers before choosing:
Telekinesis: Around the same power level as the guys in Chronicle.
Teleportation: Like Spartan 3.0 who can not only teleport himself but other objects or people without touching them or even being in their vicinity.
Telepathy: Ability to read minds, absorb information, but no direct ability to control them outright. You can enter people's dreams or take them into an astral plane with you - but they always retain their free will. You can control this ability so you are not always hearing voices.
Time Stop: Sort of like Hiro's ability to stop time - but not his other abilities. Basically, think Zack Morris from "Saved by the Bell" and his "time-outs".
Healing Factor: Logan's HF
Shape Shifting: The ability to change into any other person or animal.
Pretty sure if that was your only goal you can do more with the other powers (without resorting to, basically, mannequin rape).
TK = ultimate vibrator.
Shape shift your way into some game.
TP = take her into the astral field as it's happening and have a full sensory overload beyond what you are used to.
Telepathy. Without the drawbacks of hearing voices, the ability to absorb information is way too tempting. Becoming a master of whatever profession you wanted, the assimilation of any skills, etc. Any adrenaline rush you could get through shapeshifting, you could get by entering someone's dream or messing around on the astral plane. While you can't control their free will, you might be able to mess around with their perceptions of the world in small ways, and I imagine sensing something through another person's eyes/nose/body to be a perfectly trippy experience.