All my flying is for leisure and paid for by me. I enjoy long haul travel but this represents a fairly considerable outlay of cash whoever I fly with. When I'm spending large sums of money I want to feel a sense of security. I trust BA with safety and I also trust them to deal properly with any issues and problems that may arise (and my experience has borne this out).
However, my local airport is EDI and I will do a direct short haul hop with other airlines if available rather than considerably extending short haul journey time by going via London with BA.