That is tough, but for my part, and most of my friends I talk to, our hatred for ASU is growing rapidly and approaching Holy War level.  Most of the people I talk to really want the streak to hit 10, but would much rather hammer ASU than BYU.  I would have to say ASU.  I know you don't want to hear this, and while beating BYU has plenty of value, it doesn't help the goal of making it to the Rose Bowl.