Merritt, Each of those carts is going to work, but don't limit yourself to those just because the host offers them. This probably just mean they can install the scripts for you at no charge.
Also to note: the CubeCart they give you is most likely version 3 (the free version). CubeCart is now on version 4.3+ and does offer a lot more (but it is not free).
Choosing the right cart software is one of the most important choices you can make, since it is not easy to go back and change once you have your store setup and running.
