As long as you don't get caught up in this: https://www.flyertalk.com/forum/air-canada-aeroplan/1909878-internal-ac-memo-warns-delays-unloading-some-flights-yyz-due-cbsa-shortages.html

The jist of it is that there is the potential of YYZ customs/immigration delays due to agents being moved to the physical border to deal with people walking across the border from the US to seek refugee status in Canada.

It wouldn't change my plans, but since you're looking to make decisions based on the lines I thought it was relevant.