What is the best shopping cart solution?

I have used E-junkie.com in the past with no issues. E-junkie provides with a copy-paste shopping cart which you can simply paste in your website. It's very easy to implement and simple to maintain. It only costs $5 a month and your buyers can pay you using PayPal or google Checkout (both of these accept credit cards too) You can try their 7 days trial period to see if it works for you http://www.e-junkie.com/

Because not all shopping carts will fit everyone's needs; You can always compare shopping carts at http://www.ShoppingCartsForWebsites.com