I prefer Google Checkout / Paypal, as I don't have to type in my shipping information. Generally, though, I prefer to buy from Amazon, since I don't have to type anything -- click a button, it shows up at my house in a few days.

Amex. Great customer support. They also offer buyer protection program so Amex will reimburse you if the product you bought breaks or is defective up to a certain amount.

If your card number was ever stolen because of a shoddy merchant, or if you got screwed over on delayed shipping or a broken product, Amex has your back.

I have been using amex for years now. They have the best customer service. The dispute process is really simple/easy. Whenever, I have to buy something from a place I haven't heard off or looks a little shady I use Amex.

Sorry, 100% disagree. I had an AMEX here in Europe and the customer service was way below expectations. We returned all of them.

I am not sure about their service in Europe, but it has never been a problem for me in US. I have multiple AMEX cards.

Inside the US. Prefer just using my Visa/Mastercard directly.

I like to use a ShopSafe solution from BoA/Mastercard that lets me generate a different card and limit for every purchase I make online. However, I use PayPal 90% of the time.

In order of preference: Google checkout, then PayPal, then my own credit cards (usually I have either a Visa or a Mastercard memorised). I do have a Discover but only use it for large purchases (like flights) because it is not universally accepted so I can't be bothered to memorise it.

I am in the US. If I was in Europe, I would prefer the direct-to-bank debit system many countries have.

Norway: Visa or PayPal, please.