I don't have an answer because I don't know very much about Poly and Clovis West at this point -- except that they're very good.
I think Mitty will be favored against Salesian because of depth of talent and continuity, but they were favored in the Open last year, so there you go ...
Mitty will most likely start the season in the top five in the nation, so they will be the favorite, and with the injury at La Jolla Country Day to the star freshman, Poly and CW are the Southern favorites -- maybe.
Rumor has it Clovis West will be shifted into the NorCal Open this year, which will certainly shake things up.