Mijoshop. End of story.
I have used all the shopping cart systems over a period of time over the past few years from joomshopping to virtuemart to redshop.
I have now taken to using Mijoshop which far and away blows the others out the water.
Admittedly it is not free but the cheapest version with all features is $59 (Less than £40 for us english) but this is nothing when you consider all the modules and support you can get.
Mijoshop is based on Opencart and they have now moved away from Opencart and develop it on their own yet still have most of the modules from Opencart compatible.
The backend is so much cleaner than any other system i have used.
If you are running a shop on your website then really the outlay to subscribe should be worthwhile and i cannot see how at the moment Virtuemart or Joomshopping can compete.
Redshop which I was using up until recently has become really poor and their support is terrible.
Would like to hear peoples thoughts either for or against MijoShop being the main shopping cart software?