I never took a train 'cross Canada. But, drove round trip three times.

Most of Canada is interesting (IMO), and some parts more so. I especially like meeting people, so I find a car ride really nice, though tiring at times. To me, the people factor would be missed in a train ride. But, it's a long drive (four time zones, plus), and if it is rushed, it is not for everyone.

Ontario is really big. I found the northern route, as "meself" said (trees and rocks, rocks and trees, trees and rocks, rocks and trees). However, I found driving up from Toronto, to Barrie, around Lake Superior, to Sudbury, Thunder Bay and Lake of the Woods to Winnipeg more interesting (though there is some of the too much "lake, rock, tree" thing also).