If BYU has the option to choose between the two games (GRB vs Indy Bowls), it would seem that the Guaranteed Rate Bowl is superior in almost every way for BYU.
Easier access for most fans, especially west coast fans who won't have as many games going forward.
Post-Christmas will likely get more eyeballs and again easier for travel
GRB gives BYU an extra 10 days to recover and get healthy
Money has been disputed and isn't very clear but maybe similar
More prestigious and possibly easier to beat opponent