I utilize Pinnacle Cart with one of my clients and it has worked well. Needed a few add ons, to really make it "feature rich", but a very robust cart for those looking for a solid cart. Very easy to manage and they have given solid support whenever I needed it.
www.pinnaclecart.com
Too bad I don't make money on them. Oh well, good cart.
passionspice.com is built on it.