AC is fine when everything goes ok, as soon as there is a delay (which with AC is very likely given their worst north american on time preformance) - then the trip turns to hell, as there is very little help for rebookings (lounge cant help)

I prefer the Polaris seat (especially if you are a side sleeper, you will bruise your knees on the tray table on AC), Also check the deflategate thread in the AC forum on their often-deflating business class seats.

There is no arrival lounge at YYZ on the way back into the US.
You have access to the standard transborder maple leaf lounge past US customs, which leaves a lot to be desired.....