I use Yahoo's Merchant Starter package and absolutely love it. Their setup wizard is comprehensive and easy to use. They offer excellent tools to manage my site, including various shipping options, inventory management, great reports, PayPal included, and great marketing tools which are easy to access. All of these tools are made simple, and are easily accessed from one dashboard. I cannot say enough good things about Yahoo's service and it would take a lot for me to switch! The only downside of Yahoo is the limited customization, but I used a template and found it professional looking and pretty nice.