Stealth.
"Invisibility" has a very specific meaning to someone designing a character, whereas "Stealth" has a general meaning that completely covers invisibility as a concept. If I want to play a stealthy hero like Batman, and I'm looking for powers that would fit him, my eyes fall on "invisibility" and I think "no, that's not appropriate. He can't become invisible, he's just stealthy."
Conversely, let's say I'm designing a character who can in fact become invisible. My eyes fall on a power named "Stealth" and I think "perfect, that fits my invisibility-using character just fine, her invisibility allows her to be stealthy."
Powers should have broad appeal, and Stealth appeals to anyone who wants to be hard to see. Invisibility is much narrower.