For certain destinations, Southwest has more of the flights I need. Chicago to ONT? Have fun flying one of the legacy carriers. Chicago to SJC? I actually considered flying Alaska Airlines because the price was good, but decided against it since it required a change of planes (in Seattle!) and a long layover, plus I'd have to fly out of O'Hare. WN gets me there either nonstop, or with a change in Denver. From nearby Midway!