I'd LOVE to fly. While invisibility lends itself to many useful and potentially naughty situations, I'd still choose the power of flight.
Mobility. Freedom. To soar the skies with the birds and to strip yourself away from the shackles of gravity. To feel the wind rushing past your face as you cut through the air. It's one of my fondest dreams. Human beings have always sought this gift, but airplanes and hot-air balloons are nothing compared to the possibility of taking to the air under your own power, your own will.
<sigh>
And
Spidey, sweetie, it's "INCORPOREAL." The other terms for the ability to pass through solid objects are "phasing" or "insubstantiation."