I don't want to spread misinformation as my knowledge is a few years out of date, but used to be OO was not Cat III rated, while QX absolutely is. That can make quite a difference when the weather isn't so nice...
This was exactly what I was going to post.
Was interesting going to FAT; but kinda blew some connections heading to LAS. [My ANC-LAX-SFO-LAS made a stop in FAT as wx was marginal and OO did not have the same tech as AS (or QX). So we made a stop at a new airport for me.
This was like 2-3 years ago, I imagine OO is still the same however.