Air Canada has been the most passenger friendly airline I have used to travel from the U.S. to London and back. The luggage transfers and check-in process are very convenient and move you along quickly.
AC uses very small planes with little storage space for short hops and may not have room for your carry on luggage. Be sure to pack what you need for those flights in your personal carry on that is stowed under the seat in front of you.
A pillow, blanket and earphones are waiting in each seat when you board the flight to go overseas. The seats have a little more leg room than other airlines I have used. They offered new release movies as well as older titles for entertainment and the viewing equipment was in good condition. The in-flight meals were good and there were multiple snacks available. I have booked Air Canada the past few times for this trip and will continue to choose them over the others I have used.