I'd say it all depends on what you're looking for. Montréal, Toronto, and Vancouver each have heavy-rail, longer distance, commuter trains.
For urban rail: Montréal has their Métro, an unusual rubber-tired subway system; Toronto has an extensive network of streetcar routes; Vancouver has the SkyTrain; while Ottawa, Calgary, and Edmonton each have some minor light rail operations. If you want buses, they're all over the place, but this isn't buses.net.
If I had to pick one, my choice would be Montréal as there are two commuter train routes there, one electric, that run both ways during the day and also on weekends. There are a number of others that operate weekday rush-hour only.
Ken V. Moderator: Most things Canadian.
Any time could be train time!