NUIC has had a team in the 1A or 2A title game in all but 4 or 5 years since 2000. Seems like they should be towards the top of a best conferences list.
With regard to your comment and rocketnation's above, I ranked the conferences in an absolute sense rather than a relative sense. In other words, for example, would the top three or four teams in the Northern Illinois Ten Conference (NIC10) be likely to defeat the top three or four teams in the Northwest Upstate Illini Conference (NUIC)? I was supposing that they would in most years.
If we were to rank the conferences in a relative sense, then the rankings would be different. Again, in other words, if the conferences were ranked with respect to their strength in relation to the class level(s) in which their respective members play, then the rankings might look more like this.
1. CCL-Blue (Eight state championships in the last five years.)
2. CCL-Green (Six state championships in the last five years.)
3. CCL-White (Three state championships in the last five years.)
4. Big Northern (Three state championships in the last five years.)
5. Illinois Central Eight (Three state championships in the last five years.)
6. Northwest Upstate Illini (Three state championships in the last five years.)
7. Southwestern (Two state championships in the last five years.)
8. CCL-Orange (Two state championships in the last five years.)
9. Fox Valley (Two state championships in the last five years.)
10. Central State Eight (Two state championships in the last five years.)
The method used here is somewhat simplistic, but it gives an idea of what a relative ranking might look like.