Of the Chinese carriers, Hainan is by far the best. I assume they would operate from Beijing as that's where they are strongest. Their long haul product compares favourably to European or American competition in its own particular way.
Flying from or transiting through Pudong is a disaster in comparison due to most domestic destinations leaving from Hongqiao and delays on most departures.
Hainan fly domestically from T1 in Beijing where many many years ago a Shannon airport company ran the duty free. I'm showing my age now.