I only root for A&M. My oldest graduated from A&M, so I don't have another program to root vicariously for. We are a family of Aggies, from my dad to my son, my BIL and his kids, and my cousin.
Over the years, I have liked a few other programs for various reasons - USC for the fight song and cheerleaders, Michigan for their helmets and fight song, the Gators for the chomp, FSU for the flaming spear, and Mississippi State when they had Jackie and blasted sippy in back to back years. But I'm sure as hell not rooting for any of those rather than the Ags after the Ags lose an ugly one.