I really like the signature suite at YYZ, I think it’s better than the Polaris lounges I’ve been to. And the Cafe at YYZ domestic is really nice too.
I find the seat, service, and food roughly comparable to UA. One thing I don’t like are the short flights from YYZ to Europe, I prefer even just the extra hour I get from ORD.
Each flight was delayed on AC (some short, some long).
Biggest oddity I had with AC were dupe seat assignments and a lot of seat poachers, but that could have just been bad luck on my end.