We have been in business for over 11 years. Originally we used Marketworks which got bought out by ChannelAdvisor and ultimately they ended all support for Marketworks and pushed us onto the Channeladvisor software.
Too American, not at all designed for the British market. Big, brash and unsupported sales techniques and we decided to look elsewhere.
Around 5 years ago we joined eSellerPro. It was very different then to how it is now but I still believe its the best solution for us and any British multi channel online retailer.
Its now rebranded as Volo. I'm sure I have probably been the biggest pain in the ass customer they have ever had but their support has been good. My business has changed and my requirements have changed. They work with me. Preferred it when I knew everyone that worked there and had a personal relationship with them all but hey, its a great software, of course it was going to grow and change.
Always developing their software and its easy to customise to the way you need it to work for the way you run your business. We currently use the eBay and Amazon feeds and 6 months ago we moved to a Magento website, which connects (not perfectly yet) with the Volo software