I have to disagree with the advise of choosing a company based on your fleet. The routes/fleets change. Maybe not in a year, but they certainly change. New fleets are being introduced, and route requirements are constantly changing. You may change a fleet or be given an offer you can't refuse
Choose a company where you will feel comfortable, and most importantly, choose a city where your family (or if you don't have one) and/or you will feel comfortable.
Doha and Dubai are different. Yes, both are in the gulf, and only a 50 min flight apart, however they are different.