Living in Canada, I think we’re pretty lucky to take Air Canada. Recently I had to fly on United metal and the experience is not great.
First, I was a bit confused by how their inflight entertainment system worked. They have a partnership with DIRECTV and everything was organized into channels rather than a VOD service. If you missed the start of a movie, well it’s like catching a movie playing on TV. Not having the control to watch when you want seems backwards in this day and age.
The flight attendants also seem different. They say the same courtesy words but there’s a hint of haughty attitude. AC agents are not all great, but they seem to be more laid back.
AC also spends money in a better way in their lounge. I don’t drink but I notice the magazines. AC has a wide selection of Canadian magazines that you can take with you. The United lounge only has copies of their own magazine.
Also, the AC Signature Lounge dining service at YYZ is amazing. I’ve never been to a Polaris lounge but the Signature Lounge seems without peer at least in North America.