Thank you for your replies! The price for flying over YYZ is identical as YUL in the Tango plus fare (which I will book). The layover is slightly longer in YYZ, 1h 45m, compared to YUL that has a 1h 25m layover.

I have never been flying with the 77L yet, therefore I was curios, on the other hand I will fly 77L back from YVR to YYZ on my return and then in YYZ board LH:s 346 to FRA (or should I rather fly AC on my return as well? Then it would be 77W instead of 346, the price and connection times is very similar).