BA, Ryanair & Easyjet
I have never flown with Ryanair or Easyjet, and don't intend to - if I can possibly avoid it.
However when I start making plans for a trip ( I only travel for pleasure ) I do consult the ryanair & easyjet websites. I also have direct access to my travel agents reservation system, so I can see fares, rules & availability on "full" fare airlines before I do book.
To date almost every time I have been able to get reasonable fares with a slight change of travel dates on ryanair, but easyjet has always had the most excruciatingly painful high fares.
Accordingly I now almost only just check easyjet website out of curiousity to see how much I will be gouged.