As a student pilot, what is the best aircraft to rent or purchase for completing my flight training and building flight time?

We generally don't recommend students buy planes. Owning a plane is much more than the cost, managing the maintance or being unable to train while the plane is being overhauled is a pain. At Flex Air, we do all our single training in the Cessna 172 series. It provides a good introduction to flying at a reasonable cost and is a very safe and reliable plane.