My rule of thumb is that if I am on a trip that I'm reasonably confident won't require any changes, last minute shenanigans, tight connections, or special service (or anything else that requires any sort of extra service) I will be fine with a 3rd world carrier such as EK. But if there is any chance of irregular ops or brain surgery of any sort, you're better off with a US/EU carrier (and, intermittently, the larger Asian flag carriers), which is much more likely to have a culture of customer service and going the extra mile to make things right. Not guaranteed, of course, but IME with EK and a host of other third world carriers you are just SOL. I don't know if it's training or culture or what, but they just don't seem to care when things go awry.

I should caveat that with one notable exceptional incident. Going from KGL-SFO last year (KQ and CI) my flight out of KGL on KQ was canceled due to mechanical failure (and with only one flight a day, that meant a 24 hour delay). Because my connecting flight from NBO-BKK only flew every other day, my arrival in SFO would be delayed by two days. I had a meeting in SFO I would miss and told KQ this was unacceptable. KQ rerouted me through LHR and put me in J on British Airways LHR-SFO the next day, which I believe was beyond what they were strictly required to do. I appreciated it, and have flown KQ to and from KGL ever since.