In 1998 I flew KLM business class from Toronto to Amsterdam and then on to Dhahran, Saudi Arabia, and made the same trip in reverse. The Boeing 747 seats in business class (which were "up top") were large and comfy and reclined 155 degrees (compared to 127 degrees on Air France's business class). The KLM service was exceptional, as were all the usual goodies, including personal entertainment centres attached to the arm rest.

In checking, it appears that KLM offers sleeper seats on its Boeing 777 flights, some of which fly from Toronto to Amsterdam: http://tinyurl.com/25bqj

If comfort is paramount, I would look for airlines with business class seats that convert to flat or almost flat beds. Here's a website that compares them: http://www.luxurytravelsource.com/sleeper-seat.html

Cheers, Pat, Alberta