I need something that is competitive to Volusion/Magento in terms of features. Cost is not an issue.
Thanks
I've been watching the situation around shopping carts for past 5 years very closely. Imho the only carts that are worth trying :
I've used all of them now. The first 3 are sort of out-of-the-box. I prefer jadasite and shopizer, because they are opensource projects and you have all the Konakart's paid features for free in Jadasite. And from what I know they are even better. You can install these shopping carts and go.
If you are skilled developer and want to spend a month or two playing with a nice technology, or you need a solution for a middle - big businesses, try ofbiz, because ofbiz gives you a platform for building enterprise class e-commerce solution.
Finally, Broadleaf Commerce is somewhere in the middle. I blogged about it recently. Great technology stack, very experienced project lead. You have to have at least a year of java dev experience, because the way of integration and customization has "integration" nature, based on Spring beans/services/controllers or persistence entities overriding/merging/adding ... But it is very simple principle and I was able to work on a custom shopping cart even the same day when I checked out the code from svn.