Go for alto.
If the cars are a few years old chances are they will require work, even if it is not visible at the moment.
Vitz is a popular car, but getting an old vitz is not recommended, plus it has a low ride height, and wont be very easy to drive on rough roads.
Alto on the other hand has better ground clearance, easy to repair.
just make sure you get the A/c working nice, and the alto will be fine.