Over many flights, TK have let me down badly only once: and they have surprised me in a nice way many more times. Istanbul airport is what it is.

I've had lovely experiences flying QR, but the dysfunctional nature of their operations has developed into farce more than once. I have been frustrated to the nth degree by the airline's helpless efforts at providing customer service.

So...fares and schedules being equal I'd chose Turkish. Where QR offers better fares, or a shorter journey time, I'm happy to use them. In short, I'm a tart