When i first started commuting to this job (8 years ago) i had the choice of a car, motorbike or bicycle.
The car quickly lost favour as it was at the mercy of the other traffic and as such was the most stressful way to travel.
The motorbike was equally frustrating, dodging through the traffic at low speed not being what it was designed for.
The bicycle soon became the vehicle of choice since i could go at my own speed, i could guarantee the journey time most days and it was keeping me fit.

If i was starting out now, though, the cost of driving would probably be the main push.