AC's sardine can better pay me to get on let alone paying more money for it.
Seriously though, economy class nowadays are more or less the same. There's very little comfort to be had and only designed for you to get from A-B. Seats barely makes any difference and food/service, if you actually care, just bring something on board. On long haul flight like YVR-HKG, expect to spend a day after arrival to recover from the trip.
If I were you, I'd do the following: find the cheapest flight if it's just A-B and use the money toward a good meal upon arrival.