[sensei]

What if you split the contest up into 2 categories? Pieces with lyrics, and pieces without lyrics. That would settle the issue (at least somewhat) of some people not enjoying the instrumental tracks and others not enjoying the songs with lyrics. Of course, then you would probably need to have 2 grand prizes and double the amount of runner-ups, but you could always make the runner ups smaller (2 or 3 for each category)...