Many Bus and Skytrain passengers know of two or more similar routes that will get them to where they want to go. The decisive difference between the two may be as simple as which one will leave sooner. Other considerations might include

1. How much time will be spent in the cold or the rain, or in an otherwise uncomfortable environment
2. Which route is faster
3. Which route is less risky (more frequent departures, so if the target bus is missed, how much time would be spent waiting)
4. etc.