php shopping cart need advice

I am shopping for a shopping cart(no pun intended), few requirements:

• php written
• supports several method payments: visa, mastercard, paypal
• easy integration
• well tested and stable
• html could be edited to make it look like a part of web site

what are the big ones out there to use?

From stackoverflow

• Hi,

  Magento
  Zen Cart
  OSCommerce
  

  These are the 3 best I've worked with.

  gnomixa : thanks. Which one is the easiest to integrate?

  yoda : Magento might be the simple one.

  gnomixa : thanks. one more question: Zen Cart - does it have url rewrite?(SEO friendly)

  yoda : yes, but via third-party scripting : http://www.zen-cart.com/index.php?main_page=product_contrib_info&products_id=231

  gnomixa : I read some reviews about Magento; and all of them claim it to be very hard to understand. What's the learning curve like? Is it a day, week or more? Thanks

  yoda : the learning curve depends on you really. If there's a system easy to learn, you can't expect much of it, basically. My choises based on the documentation and capabilities they have.