As mentioned DC is very simple to power. If it doesn't need to reverse, it's a single transistor.
AC induction motors have a much more difficult driver, usually 6 transistors. The proper way to drive them is somewhat motor-specific as well.
That's not to say an AC drive isn't a GREAT project! It's more difficult but you'll learn more. I suspect your cart could outperform a DC motor. Also, if you're doing this as an alternative energy project, DC motors don't really do regenerative braking whereas AC motors do. While this doesn't come up much in a go-kart, it's a very important principle.