I prefer Southwest. It is usually going where I want to go. No Bag fees. I really don't mind their boarding procedure and if I want to board early, I pay a small fee (less than what other airlines charge for "premium" seats).
But, what I like best about Southwest is their flexibility when I cancel. I have a year from the date of purchase to use the funds. I can use the funds on any route not just the one I cancelled. Also, I can use the canceled fare to pay for a ticket for someone else.
When my son was in school, I would make flight reservations when the fares were cheap. If I had to cancel, so what. I would just use the funds for a future flight for him or someone else in our family.