Pop Warner will bring way more crowds to the Values. Mousefest by comparison just isn't that big, and they participants are spread out all over the resorts. I haven't looked at the dates for Mousefest this year but I was there a few years ago and Pop Warner and it were happening at the same time. You could definitely find the PW kids in the resort at any given time. Not the Mousefest people! In fact I think I only met 2 or 3 the entire time, by accident and that was at the parks.
But as long as you are tolerant even PW isn't that bad. The only thing we had a big problem with was in the food courts at breakfast and late dinner times. If you keep a sense of humor you can get through it. If you have tired and starving children that might be difficult.