Distance is definitely a factor, as is frequency. I'd prefer public transportation systems (trains, buses, planes, etc.) if it's a longer and occasional trip.

Distance is definitely a factor, as is frequency. I'd prefer public transportation systems (trains, buses, planes, etc.) if it's a longer and occasional trip. For short, regular, frequent travel, i.e. a commute? Give me a personal car anyday. But my opinion is jaded from the awful urban public transportation systems we have in the US. Give me something like what Tokyo, Seoul, etc. have, and I might prefer public transit for commuting too.