[support] Most suitable ecommerce module

Hello support, I'm planning a drupal based ecommerce website. There will be an affiliate role for buyers with a special % discount on each purchase, and a custom discount for some of these users (affiliated) . The shop will count many products, probably around 1000. Finally we'll use a custom payment gateway with a local bank api. I read about ecommerce module (of which I got a book by M.Peacock,2008 about v3 on D5) and ubercart module. After searching on the web for comparison of these two modules, I've started some days ago to create 2 different test sites on D6. Not yet tried to customize theme or work with APIs. I'm still confused.. Can somebody give me any hint about ? Thanks a lot, Luca