I've been using oscommerce most recently, but have been unhappy with their search engine friendly url contributions, which seem buggy and poorly supported. I like their STS(v4.5) templating for the most part. I'm looking for a php shopping cart that has excellent capability in both customization of the url and flexible templating. Being able to keep both the look and feel of an existing html-based website, along with the url structure would solve a lot of problems. Being able to style something css based rather than oscommerce's table based structure would be wonderful. Any recommendations?
X-cart with the DSEFU mod (can I say that here?). Its the only cart I can recommend as it is the only one I have recent experience with. I did try the other popular SE friendly url mod for X-cart but it required some functionality not offered by my web host so I switched it for DSEFU.