Well I have not flown these airlines, but from friends who travelled to China all the time...
1. In-flight Service - China Southern... CZ
's meals and IFEs seem to be more advanced... IFEs at all classes in its fleet of Boeing 777s + meals are pretty good. For USA routes, it has a Businessfirst product, and a economy plus/premium service, and regular Y service. Air China is second, and I have heard much negative about China Eastern, especially on the regional flights. My friend who flew between HKG
and Fuzhou used to fly MU
due its thrice daily flights, but later changes to KA
once daily and less convenient because the F/As at MU
are so rude.
2. I think it is a rather unfair question because CZ
is relatively young... but it seems that CA
has the most accident rate, and CZ
are more than fine, especially they have the younger planes -- Airbus A340-600s and Boeing 777s, Airbus A319s & A320s.
3. Air China is leaning towards international. China Southern is more about Southern china flying and then China Eastern is about the eastern part of China. AC
less domestic... but CZ
based on Guangzhou and MU
based on Shanghai... should have about the same domestic coverage... MU
4. Internationally -- CA
should be top, followed by MU
and then CZ
... but CZ
seems to be expanding more than CA
5. Fleet -- CA
has a wide range of aircraft -- Both Airbus and Boeing; MU
has mostly Airbus with a few MD
-11s, and CZ
are both Boeing 777s and Airbus A319/320... MU
gets a bunch of new Airbus A340-600s recently, so I will say MU
is younger than CZ
6. Economy Class -- CZ
scores the highest with IFE on its Boeing 777s. Everything should be similar and CZ
seems to be friendlier group.
7. Business Class -- CZ
again with its Premier Business Class... but all three Chinese airlines should have a variety of products... some better and some worst... very hard to judge.