If you frequently fly solo between Shanghai and Hong Kong, flying Cathay Pacific or China Eastern out of SHA are your best options. SHA is quicker to go through for both arrival/departure than PVG. Cathay Pacific offers much better food than China Eastern and should be your #1 choice.

How I decide on what best is

In no particular order, the factors that are most important to me for <6 hour flights are:

  1. distance to the airport - SHA always wins over PVG
  2. seat comfort - only Cathay Pacific and China Eastern can meet my 18" seat width requirement, and I prefer the 2-4-2 configuration as sitting at the "2" means potentially less interruptions by your neighbor climbing over you to get to the toilet.
  3. flights at the times I want - both airports offer sufficient choices to me.
  4. airline and/or alliance - departure times determine my airline choice. OneWorld and SkyTeam are both options but Star Alliance is not. If I am traveling during meal-time and I know I need to eat airline food, Cathay eats like a real meal. China Eastern food is not at the quality level I would even consider paying for if I saw it at a food stall. I don't care about airline alliance for such a short flight as it doesn't make a big dent to mileage awards. Cathay also has seat back entertainment whereas China Eastern does not.
  5. cost - as long as Cathay Pacific keeps it under $250 round-trip, I would choose it over China Eastern.

Seats

While there are multiple models that meet my 18" seat width criteria, there are variations for some models which means uncertainty. If you want certainty, and the least detail to remember, it's to fly the A330 for best seat width, seat pitch, and fewest neighbors. I prefer aisle seats at the "2" so there is only 1 neighbor that may have to get to the airplane toilet.

I've listed the airline alliance in case you prioritize the alliance more than I do.

Cathay Pacific (OneWorld)

Cathay Pacific is easier to remember. 18" seat width on all Airbus planes.

Feature A330-300 A350-900/1000 777-300ER
Economy Layout 2-4-2 3-3-3 3-3-3
Economy Width 18" 18" 17.2"
Economy Pitch 32" 32" 32"

China Eastern (SkyTeam)

The A330 seat widths can range from 17.2" to 17.8". If you want certainty fly the COMAC, which has 18" Economy seat width. Plus the middle seat is actually 1.5cm (0.59 inches) wider, so you may want to consider that if the pitch doesn't bother you.

Feature A330-300 COMAC C919 A321 / A321neo A320neo 737-800
Economy Layout 2-4-2 3-3 3-3 3-3 3-3
Economy Width 17.2" to 17.8" 18" 17.5" - 18" 17.3" - 18" 17.2"
Economy Pitch 32" - 33" 30" - 31"" 29" - 30" 30" 30"

Airport - PVG (Pudong)

Unless you live east of the river in Shanghai, Pudong is generally further for most people. The Pudong airport is much bigger than Hongqiao, so there is a ton more walking even after you enter it. Even with e-channel, you may find yourself taking 30 mins to clear security and get to your potentially very far gate.

Cathay

Not all flights from Shanghai Pudong Airport (PVG) use the A330. Highlighted below are the times where A330 is flown.

Flight Departure Frequency Typical Aircraft
CX 303 07:20 Daily Boeing 777-300
CX 361 08:35 Daily Boeing 777-300 / A330
CX 365 09:35 Daily Airbus A330-300
CX 319 12:20 Daily B777-300 / A350-900
CX 367 13:20 Daily Airbus A350-900/1000
CX 381 14:30 Daily Airbus A330-300
CX 363 17:40 Daily Airbus A330-300
CX 341 19:05 Daily Airbus A330-300

China Eastern

The China Eastern 8:55am flight might come with good seats. It seems around 90% of the flights would not be good seats so I would avoid flying China Eastern from PVG unless you want SkyTeam mileage.

Flight Departure Frequency Typical Aircraft
MU 501 08:55 Daily Airbus A330-300 / A321
MU 507 11:10 Daily Airbus A321
MU 509 12:55 Daily Airbus A320neo
MU 505 16:20 Daily Airbus A321
MU 725 21:00 Daily Airbus A320neo / A321

Airport - SHA (Hong Qiao)

If you must fly in the morning from SHA, China Eastern is your answer for comfy seats. If in the afternoon from SHA, Cathay Pacific is the answer as there are no morning flights from Cathay.

If you don't have check-in luggage you can enter the airport, go through e-channel, security screening, and get to your gate in 20 mins. My record was 13 mins.

Cathay Pacific

All Cathay flights from SHA to HKG are on A330, so all have good seats.

Flight Departure Frequency Typical Aircraft
CX 349 13:20 Daily Airbus A330-300
CX 335 16:50 Daily except Weds and Sat Airbus A330-300
CX 327 22:30 Daily Airbus A330-300

China Eastern

Only the morning China Eastern flights from SHA to HKG have good seats.

Flight Departure Frequency Typical Aircraft
MU 721 08:15 Daily COMAC C919 / A330
MU 5017 09:10 Daily Airbus A330-300
FM 809* 15:00 Daily Boeing 737-800
MU 511 18:30 Daily Airbus A321 / A330

*Operated by Shanghai Airlines

Takeaway

Flying Cathay out of SHA is the best if the price difference compared to China Eastern isn't that great. I would easily pay USD 30 more for Cathay just for the mobile boarding pass that works, food and seat back entertainment. If you want cheaper options China Eastern is the next best option but you may or may not get the seat comfort you want without first doing more research.