A relative was an international reservation agent for a major airline.
By far, SFO was the worst for on-time with all the fog delays. Because I traveled to Asia every 8-10 weeks for a few years, I was advised to avoid SFO at all costs.
My anecdotal experience on those few times when it was not possible to avoid SFO was the the workers were always grumpy and the passengers picked up on it and mirrored the discontent.