I'm not sure the poll was worded clearly enough that I understand it's intentions.
The essence of what makes a Drum Corps a "Corps" is everyone working as a unit to achieve one end.
To ask "Which is more important, the music or the visuals" is like asking "Which is most important for a pizza, the crust or the sauce?"
To which the answer is "Without both, you might have something tasty ... but it just isn't a pizza!"
I wonder if the question was more about all of the "pageantry" that is going on during most Drum Corps shows now?
In that case the question would be more along the lines of,
"What is more important to make an award winning pizza, a really good pie (crust and sauce) or having tons of exotic toppings?"
Mmmm.
I gotta go get a snack now.