Flown both EVA and AsianaAirlines.
Both excellent choices.
I prefer AsianaAirlines of the 2
Never flown the Mainland Chinese airlines but have read some not so good reviews so tend to avoid.
All it takes is once experience with a mainland China airline and you'll pay the extra cash to avoid them. I've flown Air China (business) and China Eastern and both flights had the cabin fill up with the smell of cigarette smoke. Turns out the pilots were smoking in the cockpit.
My personal favorites are EVA Air and Cathay Pacific. Premium economy for the best bang for the buck.