If I were picking new for today, I'd use Stripe + Spreedly if I were a US developer. (I've used both separately.)
That said, I have no major complaints with Paypal. (Nor do most merchants who use the service. You just don't read blog posts like "Day 1,349: Paypal continues to provide very cheap services without requiring a merchant account. Details pretty much same as Day 1,348."
Why not Samurai? I looked at both stripe and samurai in conjunction w/ Spreedly and came out on the Samurai end (lower prices being the motivating factor)
That said, I have no major complaints with Paypal. (Nor do most merchants who use the service. You just don't read blog posts like "Day 1,349: Paypal continues to provide very cheap services without requiring a merchant account. Details pretty much same as Day 1,348."