Which form of m transit do you prefer? Monorail or subway?

Pretend you live in a city and there's a new ballot in the next election. The city council decides to install a m transit system. They cannot decide whether they should build a monorail or subway. Which would you choose? A subway is out of the question where I live (Austin, Texas) because there is too much limestone and bedrock in the soil. Just pretend that the terrain where you live is suitable for either though. Which would you choose and why?