Zencart had been very solid and been around for quite sometime.
Don't really like cubecart & have no comment on ubercart. Never try before.
Magento & prestashop are the newest ecommerce shopping cart to consider.
Prestashop is quite good and easy to install. Have all the features you need to run a shopping site.
Magento is power-pack with more advanced features.. still alittle buggy but worth checking it out. Installation is not so easy. However, you can always get your host to install for free if you need the help.
I like Magento then cs-cart personally as a shopping cart.But the biggest thing about a shopping cart is find something you like the interface on, and 99% of them are template based, so you can make it look like you want it to.
