The previous monthly contest specified a specific musical work and the contestants simply submitted their recorded performances of the piece.
Thus, there was never a situation where people had to choose between a tonal work and a freeform work.
Here are a couple of thoughts on a monthly contest:
1) A person may win up to three contests per year. This so that people have a chance to win.
2) The site moderators select judges who remain anonymous. The contestant's identities are not given to the judges (thus, the entries would be .mp3s rather than video). The idea is so that the performance is evaluated in a non-biased manner.
3) Some months will designate traditional/classical and others will be experimental/non-traditional.
I think the problem with voting is that often people with large friend's lists (i.e. on Facebook, etc) may simply ask people to vote for them and the whole thing devolves into a popularity contest.
Also, I think each monthly contest can have different requirements -- that is, some months may require people to submit solo theremin tracks without effects or accompaniment, some months may encourage fx, others may encourage new arrangements of old songs. One of the issues that surfaced before was that some of us have studio resources that enable advanced arrangements/orchestrations while others will record with little more than a theremin and a microphone.
Ultimately, the idea would be that this would generate interest, encourage people to play and improve, and - well -- just to have some fun.