Being a web developer, I am usually asked to make a website for a business. Business operate on money; therefore, usually some sort of selling is required. I have used both paypal and google checkout to process credit cards, there are advantages to both, and cons to both. Paypal has been around for many years, and I first helped my brother in law (Jon Lewis) start his online business using paypal. Paypal was good about fixing orders, but has been known to reject many credit cards due to its strict processing credit card checks. I have implimented Google Checkout on a site of mine, and am very pleased. Paypal is more popular, so more people are willing to use it. However, Google Checkout is as fast and efficient as checkout out gets. So here is the run down:
Cost to operated. Both paypal and Google Checkout offer similar fees for running a credit card. It is a percentage of the sale, no monthly fees, and both are fairly close in price. Google Checkout is a little bit cheaper, but probably not enough cheaper to be worth mentioning.
Ease of Implimentation. Paypal is about as easy as it gets, place a button, sell a product. This is good, but does not offer flexability. They do offer more advanced solutions as far as Integrating with your site throughout the entire transaction, however, these require https (encrypted) websites and custom shopping carts. Since it is usually more hassle than its worth for a quick ecommerce website, I will leave these features out. Google Checkout offers the same, place a button, sell a product. However, they also offer an intermediate step up for those without an https website. With this method, you form a shopping cart in your page, encrypt it with your merchant id (which nobody should know), and submit it via a button to Google. This allows you to guarentee nobody has altered your shopping cart in transit, since only Google knows the merchant id to unlock the shopping cart. This method of implimentation is what I recommend for a balance between functionallity and ease of setup. The third method is available, but requires a secure website.
Features. I am not sure how far paypal has evolved since I last used it, however, Google Checkout has an option for almost anything and everything. With the second method of implimentation, features such as return URLs, Modify Cart URL’s, Cart expiration date, varying shipping rates, tax zones, shipping location limitations (eg. All 50 States).
In my opinion, Google Checkout will gain ground due to its well developed, highly customizable, easy to work with interface. It clearly explains each of the 3 levels of implimentation available.
As I was about to offer a link to the 3 levels of implimentation, they have now split it up. Level 1 got put into its own category, so now, levels 2 and 3 are now levels 1 and 2 respectively. I recommend Implimentation 1 on this page Google Checkout Developers Center.
I have developed my own shopping cart system for Google Checkout. Ask questions and I will gladly answer as time permits.
Jeff