But you won't be getting your money's worth if you use only their prebuilt functionality. The key factor may ultimately be the type and caliber of programming talent you either have on hand within your organization or can easily recruit. Both iCat and Intershop require you to learn a proprietary language to extend the products beyond the functionality provided by wizards and templates. The latter two are more popular development options, but you'll still need the right people to implement them. Integration with legacy systems is another consideration.
Most products here have hopelessly inadequate data-import facilities.
Hooking into existing accounting systems, the ideal scenario for truly putting your existing business online, is effective with Microsoft Site Server if you're using Microsoft BackOffice systems, or IBM Net. In defense of most of the vendors, however, legacy systems are usually databases and can be integrated by using the scripting or language capabilities the products offer. But again, that means that your buying decision is colored by the level of programming or Web expertise you have on hand or need to hire. Yet another item to consider is your ability to link to inventory and fulfillment systems. Commerce, for example, offers built-in inventory control that will let you set inventory levels and sync with an actual business if needed.