I think it's very close between X-Factor and the Voice, even though I don't plan to watch the Voice, but I'ma give it to the X-Factor because of Simon and L.A.
X-Factor. They get along so well, they're all honest, and like a family.
There's always that 1 Judge (usually a girl) that ruins everything, always says "Yes" to even sucky performances because she's too nice (Paula during American Idol), etc, but X-Factor has none of that.