The AC seating you find on YYZ-LHR is similar / indentical to AC transpac flights save the YYZ-HKG route.
I would probably fly YYZ-JFK/LAX-SIN/BKK-HAN (SQ via SIN or TG via BKK) but I don't mind long flights. If you want to break it down:
YYZ-ZRH/FRA/VIE-BKK/SIN-HAN might be better