Hainan is IMO the best mainland China carrier. The problem I have with it is the seating config. No pods on B787 and the entertainment options are typical china government censor approved crap. (Big difference from the robust and exciting EVA entertainment menu with some of the best Asian films available in the air. EVA will often feature great mainland China sourced historical based epics, that I certainly have never seen on China based carriers'entertainment listings.) If making a connection, Hainan sucks. I have a difficult time using it for SIN or BKK because of the conection schedules and to be blunt I detest transiting in China. If I have to transit in Asia, then AC's got great hubs in TYO and HKG. The staff at TYO and HKG beat anything the mainland has to offer. There are only 3 big airports in the world where you know that if it is physically possible to make a tight connection with your bags, it is going to be at TYO and HKG with TPE and SIN close behind.

Ok, some people aren't a fan of Asian cinema, but like to eat. As food is a personal preference, all I can do is point out that Hainan gets superior reviews to AC. Want a clean aircraft and a clean lav? Well, it won't be AC, that's for sure. AC FAs won't do cleaning because they are too good for that and some AC pax are disgusting people.

Speaking of which, Hainan attracts the higher end pax in J, often senior Chinese company personnel, and Chinese government government and military officials. The lower tier folks ride with the repulsive Air China. Highly unlikely one will encounter the heavy smoker coughers, and nose pickers one encounters on the Air China and Air Canada flights. High end Canadian pax of course prefer wonderful EVA.

Personally, I try to avoid congested Chinese airspace. I would rank it along with Korean airspace and tarmacs as an airline disaster waiting to happen.