I prefer the seat comfort and the pitch in AC J class compared to LH (currently). The food and service is slightly better with LH. They are both good airlines in J and I go back and forth between the two. The deciding factor often time boils down to schedule, transit time, and current promotions (price and/or bonus mileage).

Have a good trip.

I agree with the assessment on Austrian Airlines. If you have never tried it, give it a try. However, Austrian Airlines do not fly that frequently from YYZ or YUL, so you may need to be quite flexible with schedules.