Coincidently enough I just came from looking at x-cart for a client. It appears to be a pretty slick system. The only thing holding me and my client back from is the fact that it runs on a membership basis where buyers have to sign up before they can purchase anything. This is cool for marketing purposes and targetted email etc. but may also scare some buyers away.
There are plenty of webmaster-friendly carts. Drive all of the demos that you can. Since you'll be the one using it (and just starting out), you'll need to test several demos to see how the administration is set up. Some I've had experience with (including 3rd party hosted carts) claimed "easy interface and user-friendly" - but required CGI knowledge and careful HTML manipulation.