Which acquiring bank or partner works best with QuickPay for international payments?

If you are looking at non-tangible good, digital delivery, Plimus is a good option to check out. Alternatively, I would recommend www.2Checkout.com - they deal in the international market and are well established.

Here is a blog post I did on some of the companies in the field:

http://www.webscopia.com/2010/11...

If you Google for "online payment processor international" you will see quite a few options.