Every airline will have its good and bad points. BUT, I know a far few people in Emirates and all of them LOVE it.
Whoever is saying Emirates pilots will be shocking tired etc simply has to answer why my friends usually have 15+ days off a month!!!? VERY good rosters. Yes you may do big trips but you are looked after exceptionally well compared to any other middle eastern RPT carrier.
Actually, Emirates is run by westerners who have set up a very fair system, with seniority number based upgrades etc.... and they are expanding as well, so do your time and you will get offers for upgrades!
So my choice would be:
#1 Emirates
#2 T-had
# Qatar LAST! especially if your given 320.