Am I victim of offering too many features to users?

I don't think that's the problem here. I think the bigger question is with the premise of the site: why, exactly, would I want to "debate" Coke vs Pepsi, or Arsenal vs Manchester Utd?

Clearly, I'm not your target audience-- but the fact that most rivalries have less than 100 users seems to indicate that you're not hitting your target audience, whoever they might be, if they exist.