Anyone that uses wordpress, does not have a very professional site. Sometimes you will find a very good developer that can make it do things it isn't meant to do but I doubt Wordpress is good for anything other than a free blog.
Drupal is great, out of the major 3 CMS's, drupal is the only one that is about to break into an ecommerce CMS. Is it easy? No.. you will need to hire a developer for it.
Joomla, is wonderful. Very easy to use, great support, great extensions, I can make a joomla website look beautiful. I make many sites with Joomla and would recommend it for almost everything. Major problem with Joomla is Ecommerce. You will have to more than likely use virtuemart if you need to sell more than a few items. I don't recommend using Joomla if you have thousands of products. I also don't recommend using Drupal for that. If you have a ton of products you should use prestashop or magento.