Easy PayPal Buttons has been perfect for me. It works seamlessly, has plenty of options, and is intuitive for both customers and administration.
The built-in cart, which I just started using, has been a god-send.
And now that coupon codes are included, I can offer special deals and use the codes to track what promotion is working.
Oh - and the support - it's been excellent! I had a few little tweaks I wanted to do and Alan was very helpful with suggestions of how to handle.
I HIGHLY recommend this product!!