My rationale is to let Airbus and Boeing compete with each other (price, service) to get Air Canada's business. You give everything to Boeing and they will take A/C for granted (ie higher plane prices).

Interestingly I prefer the 777's as the seats and washrooms are larger (only referring to J class), FA's don't control my shades (like on dimmable shades 787). The washrooms on the 787 & A350 are small and cramped (But I AM 6"2 AND 220lbs...not all muscle). 777's interiors are a bit louder so I can fart to my hearts content without anyone noticing or hearing it.