Given the national LDS population, I would say BYU/Utah might just lead out. TCU/Baylor is a big rivalry, as is Az/ASU I am pretty sure (correct me if wrong). KU/KSU is pretty big, but since KU is usually garbage it is one sided.
If/when Pitt joins. WVU/Pitt will be the number one in my book. The hate is real.
Your thoughts?