The thing that will drive your choice here is the functionality that you require - not what each of the e-commerce applications are capable of (some of them are really advanced functionality that you may not even require at all). Of course there is our own rokquickcart too if you only have a few items.
The market leaders are Virtuemart, mijoshop, redshop, hikashop - I can only suggest that you study their respective sites and look at their demos.
Please search forums before posting. Please make sure your post includes the version of the CMS you are using and a link to the problem. Annotations on screenshots can also be helpful to explain problems/goals. Please use the "secure" tab for confidential information.