I think the real reason flight won the splatfest is because flying is a basic human want. People always look to the sky wanting to soar through it so that goal has always been in or forefront.
I thought it was because if invisibility won, then you wouldn't be able to see Marina anymore. She'd be all transparent in the studio and oddly silent, as opposed to (To take a totally random example), say, checking all the money was still inside a bank vault.