About the command upgrades at QR...
I recently talked with a good friend who passed his command interview one year ago and they still did not schedule him for the course. Things are not going too fast there.
T&Cs must be similar in both places, salary too.
I would go for flying the 380 for EK rather than 320 for QR.
Living in Dubai is okay compared to Doha which is horrible.
Plus the 320 roster in QR is not the most comfortable I have seen.
Night turnarounds 3 nights in a row etc.
Unless you want to sleep at home with your family it might suit you.
(Sleep during the day...
)